Geo Ch.8

Day-to-day changes are related to local weather. However, the effects of global warming are noticeable.

yes

Evidence of Climate Change

Increase in global average air temperature beginning ~1890 Sea-surface temperatures show similar warming since ~1910 Anomaly:difference between a value and average of that value

Climate Types

Köppen Climate Classification System: subdivides climate based on temperature, precipitation, and seasonality Tropical (A) - blue-green; Arid (B) - yellow/tan; Warm Temperate (C) - green; Harsh Mid-Latitude (D) - purple or blue; Polar (E) - gray or white

Examples of Tropical Climates

Tropical Rain Forest (Af) Tropical Monsoon (Am) Tropical Savanna (Aw) Climographs plot temperature as red line and precipitation as blue bars

Observe the distribution of subarctic (some D-types) and polar climates (E-type)

Tundra and Ice Cap close to poles; Subarctic farther from poles Antarctica is nearly all Ice Cap Climate Dfc - Subarctic (blue); Dwc - Subarctic Monsoon (red); ET - Tundra (gray); EF - Ice Cap (white)

Factors Affecting Severity of Air Pollution

Type and proximity to source Atmospheric conditions Topography Source can be a point source or non-point source; atmos- pheric conditions can trap or disperse pollution; topography can block dispersion of air pollution or guide winds that help disperse air pollution

Examples of Temperate Mid-Latitude Climates

brussels, belgium (cfb) kyiv, ukraine (dfb) seoul, south korea (dwa) Cfb - Marine West Coast (green on globes); Dfb - Humid Continental (purple); Dwa - Continental Monsoon (pink)

One of the main contributors to global warming is the

burning of fossil fuels: oil, coal, and natural gas.

True or False. Higher-than-normal solar irradiance is responsible for the current warming trend.

false

Scientists have long-known about the correlation between

greenhouse gases (e.g., carbon dioxide and methane) and temperature.

Which ice sheet is losing more gigatonnes per year: Antarctica or Greenland?

greenland

Ice ages

have come and gone over thousands of years due to the varying amount of solar energy received by Earth.

Greenhouse gases in the atmosphere "trap" this outgoing radiation

heating the atmosphere (the same way the glass of a greenhouse traps heat for plants).

How does the current level of carbon dioxide compare to the 1950 level?

higher

Global temperatures are

increasing at a more rapid rate than can be explained by natural phenomena such as sun spots and changes in Earth's orbit.

Examples of Subarctic and Polar Climates

krasnoyarsk, russia (dfc) nuuk, greenland (et) vostok station, antarctica (ef) Dfc - Subarctic (blue on globes) ET - Tundra (gray) EF - Ice Cap (white)

Shortwave radiation that is absorbed by the surface is re-emitted as

longwave radiation.

Looking at the global distribution map, where was CO2 highest in April 2010? Hint: drag the circle on the timeline

north pole

Sulfur dioxide (SO2)

pollution from burning fossil fuels (coal) and from metal smelters High-emissions areas mostly from coal-fired generation of electricity

The organic material is extracted by drilling or mining to

provide energy for electricity and fuel.

Does photosynthesis add or remove carbon from the air?

remove

Interaction of Insolation with Earth

solar energy -> energy absorbed by land and oceans solar energy -> energy absorbed by atmosphere, clouds, and particles infrared energy rises from the ground insolation reflected by atmosphere, clouds, and particles insolation reflected by land and oceans

As shortwave radiation from the sun reaches the planet

some of it is absorbed or scattered within the atmosphere and some reaches the surface

The carbon cycle illustrated on the left shows

the various ways that carbon is added to (up arrow) and removed from (down arrow) the air.

True or False. Ice melt can lead to sea level rise and coastal flooding.

true

What is the trend of temperature (red line) since the 1880s?

up

What is the trend of solar irradiance (yellow line) since the 1880s?

up then down

These fuels are the remains of prehistoric plants and animals:

upon dying, they were buried under layers of rocks for millions of years

What types of conditions increase the risk of wildfires?

warm and dry

Drought

In periods of persistent warm & dry conditions, crops die, land is eroded, and vegetation is vulnerable to wildfires.

Tropical

(A-type)

Arid

(B-type)

Temperate

(C-type)

Harsh Mid-Latitude

(D-type)

Polar

(E-type)

What year is ranked the warmest on record?

2016

7.4

A-TYPE CLIMATES in the Köppen climatic classifcation system are "tropical," having consistently warm temperatures all year. Precipitation in these zones is primarily caused by the convergence of the trade winds along the Intertropical Convergence Zone (ITCZ), which shifts with the season to locations north and south of the equator. There are three types of A climates in the Köppen system — Tropical Rain Forest, Tropical Monsoon, and Tropical Savanna. A Where Are the Various Types of Tropical Climates? These globes show the distribution of each of the three types of Group A (tropical) climates. All three globes show all three types, but each type is discussed separately below the globes. Note that all three climate types are centered in the tropics, but they widen or narrow considerably from ocean to ocean and from continent to continent. 07.04.a1-a3 / Source: NCEP/NCAR Reanalysis dataset 1. The Tropical Rain Forest climate (Af ) is characterized by abundant precipitation year-round, which supports lush vegetation on land. Notice that over land, this type is surprisingly limited in extent, but it is more widespread over the oceans. 2. The Tropical Monsoon (Am) climate tends to occur between Af and Aw climates (following page), as in parts of the western Pacifc and Indian Oceans that have wet and dry seasons, typically due to a seasonal switch in the dominant wind direction. The short dry seasons seldom allow soils to dry fully, and so they support lush forests. 3. The Tropical Savanna (Aw) climate is named for its typical vegetation of grasslands and a few scattered trees. It occurs poleward of the other A-type climates and is therefore subject to the alternating infuences of the subtropical highs and the ITCZ. Tempera... ...dely spaced from climate Af to Am to Aw, from left to right in this fgure. Effects of the ITCZ 5. In an Af climate, the ITCZ brings rain most days throughout the year, although rainfall can be heavier in some months than others. Af climates remain under the infuence of the ITCZ, even as it migrates north and south with the seasons. 6. For an Am climate, the ITCZ is a factor in most months, especially during the summer when it is typically overhead or very close. During low-Sun-season months, the ITCZ moves too far away to generate much precipitation. 7. In an Aw climate, the migrating ITCZ brings abundant summer rain. The low-Sun-season is dry and warm as these areas come under the infuence of the subtropical highs. Examples 8. Group A climates are all tropical, so there is very little seasonality in temperature. Precipitation patterns do vary among the three types, showing some seasonality. Af climates are closest to the equator and so display the least variation in precipitation over the course of a year, whereas Aw climates are farthest from the equator and so experience the greatest seasonal changes. Am climates are typically in between in position and character. The plots below are climographs, each showing average temperature and precipitation by month. Temperature variations are plotted as a red line according to the left vertical axis, precipitation is plotted as bar graphs based on the right vertical axis, and months of the year are shown on the horizontal axis, using abbreviations for 1 of 2 04/24/21 names of the month. Observe the patterns and compare them with information about the ITCZ

7.9

AIR POLLUTION consists of gases, liquid, and solids introduced into the atmosphere by human activities and deemed to be detrimental to humans and other creatures, plants, or other aspects of ecosystems. Most air pollution consists of noxious gases and liquid, car exhaust, and smoke and soot from industrial activities and fres. A What Is Air Pollution and What Are Its Causes? Air pollution can consist of gas molecules or can be aerosols, which are tiny drops of liquids or solid particles (particulates) that are small enough to be lifted into the air. The table at the bottom of the page lists common air pollutants. 07.09.a1 Shanghai, China / Getty Images 1. Much air pollution is in the form of gases, many of which are invisible. Some gases combine with other chemical compounds to produce visible smog. Most gaseous air pollution consists of compounds of carbon, nitrogen, hydrogen, and oxygen. 07.09.a2 Wisconsin / Kelly Redinger/Design Pics 2. Air pollution can also be tiny drops of liquid, including those in visible steam and more noxious liquids derived from sulfur dioxide (SO2) and other chemicals. Steam is white to gray, but other chemicals and particles in the mix can turn the steam brown or black. 07.09.a3 / Comstock/Jupiterimages 3. Air pollution can also consist of solid particles, including dust, whether it is from a dirt road or from the coal being hauled by this truck. Tiny drops of liquids and solids in the atmosphere are called aerosols, but not all aerosols are caused by human activities. 07.09.a4 Anaheim, CA / Stephen Reynolds 4. Pollution, whether it is as a gas, liquid, or solid, can be introduced into the air in various ways. One major source of air pollution is from automobile exhaust. 07.09.a5 / Ingram P... ...nce pollution is in the air, it is subject to various processes, especially wind and vertical motion. Winds blow air pollution away from the source, perhaps clearing it from one side of a valley but concentrating it elsewhere. Stable, sinking air, as during a temperature inversion, can trap pollution close to the source and the ground, and a lack of wind limits dispersal. 07.09.c3 San Bernardino, CA / Stephen Reynolds Topography — The shape of Earth's surface greatly infuences winds close to the ground, so wind can trap or disperse air pollution. Shorelines can also infuence air pollution distribution, because water and land respond differently to heating, cooling, and winds. Los Angeles, California, has both of these infuences — high mountains that trap polluted air in the basin, and a nearby shoreline with inland sea breezes. The Clean Air Act Federal air quality legislation in the U.S. began in the 1960s. Initial attempts culminated with the Clean Air Act of 1970, which required that the federal Environmental Protection Agency (EPA) be created, along with state-run EPAs (sometimes with different names) in each state. The EPA was to monitor certain widespread (i.e., "criteria") pollutants nationwide with the goal of keeping the concentration of each below a "threshold" level deemed hazardous. Criteria pollutants are a family 1 of 2 04/24/21 of solid aerosols known as PM10, PM2.5, NO2, SO2, O3, lead (Pb), and carbon monoxide (CO). The Clean Air Act was subsequently amended many times, generally with stricter standards and heavier penalties to communities for violating these standards. As a result, air quality has generally improved in the U.S. in the last 50 years. But air quality in many other regions of the world has deteriorated.

7.5

ARID CLIMATES OCCUPY a greater portion of Earth's land surface than any other climate category. They comprise Group B in the Köppen classifcation and are subdivided into desert climates and steppe climates, with the distinction being that deserts are more arid than steppes. Deserts and steppes are further subclassifed into hot or cold categories — not all deserts or steppes are hot! In the Köppen classifcation of Group B climates, potential evapotranspiration is taken into account in addition to precipitation; an area is classifed as arid only if precipitation does not offset the potential loss of water through evaporation from the surface and transpiration through leaf surfaces. A Where Are the Various Types of Arid Climates? These globes show the distribution of the four types of arid climates — Hot Desert (BWh), Cold Desert (BWk), Hot Steppe (BSh), and Cold Steppe (BSk). 07.05.a1-a3 / Source: NCEP/NCAR Reanalysis dataset 1. The Hot Desert climate (BWh) covers huge areas of Africa (e.g., Sahara), the Arabian Peninsula, the interior of Australia, and parts of the American Southwest. It also extends over large areas of subtropical ocean. 2. The Cold Desert climate (BWk) is less common, occurring mostly in the interior of Asia (like southern Mongolia) and near cold ocean currents, like the Humboldt Current off the west coast of South America, as shown here. 3. The Hot Steppe climate (BSh) generally surrounds the hot deserts and represents transitions to more humid climates, as across the Sahel region south of the Sahara and north and east of the hot deserts of Australia. 4. The Cold Steppe (BSk) is abundant along the Great Plains and western interior of North America, in Tibet and other parts of central Asia, and in s... ...imate Conditions in Arid Climates? The climographs below convey temperatures (the lines) and precipitation (bar graphs) in areas designated Group B (desert and steppe climates). As we might expect, precipitation totals are very small, and the precipitation that falls evaporates quickly in the dry air, leaving a parched landscape. Desert Climates 07.05.d1 / Source: http://www.worldclimate.com/(opens in a new tab) Khartoum is an example of a hot desert in the subtropics. The region receives essentially no rain for most of the year. The meager July-August rains result from a slight infuence of the northern edge of the ITCZ. Khartoum is in the tropics, so its temperature seasonality is dampened and temperatures remain high, showing limited range. 07.05.d2 / Source: http://www.worldclimate.com/(opens in a new tab) Few people live in the world's cold deserts. One exception is this city in China, which lies on the fringe of the desert/steppe ecotone. Temperatures vary markedly and are very cold during the winter, but precipitation is modest. Most cold deserts have even less precipitation than shown here. Steppe Climates 1 of 2 04/24/21 07.05.d3 / Source: http://www.worldclimate.com/(opens in a new tab) 07.05.d4 / Source: http://www.worldclimate.com/(opens in a new tab) Steppe climates are more abundant and far more heavily populated than deserts. They are transition zones between desert climates and more humid climates. Precipitation in such environments is variable from year to year, with some years receiving desert-like precipitation totals and others experiencing precipitation more characteristic of humid climates. Like natural vegetation, human populations in these regions must be able to adapt to periodic dry spells and water shortages

Feedbacks in the Climate System: CO2 In and Out of the Oceans

Adding CO2 to the atmosphere causes more to dissolve in oceans, reducing the amount of warming in atmosphere (a negative feedback) Warming of water drives CO2 from the water to atmosphere, where the CO2 causes more warming (a positive feedback)

The Impact of Pollution on Climate

Aerosols and gaseous pollutants interact with energy and water in the atmosphere They can absorb, reflect, or scatter incoming shortwave energy (e.g., insolation) or longwave radiation (e.g., coming from Earth) Solid aerosols also act as condensation nuclei, so they can enhance precipitation, making the surface wetter and cooler

Feedbacks in the Climate System: Changes to the Surface

As warming melts ice, the surface albedo decreases, so less insolation is reflected, yielding more warming (a positive feedback) Warming of permafrost (permanently frozen ground) can release methane, a greenhouse gas that causes more warming (a positive feedback)

Examples of Warm Temperate Climates

Athens, Greece (csa) taipei, taiwan (cfa) lucknow, india (cwa) Examples of Warm Temperate Climates Cfa - Humid Subtropical (light green on globes); Csa - Mediterranean (pink); Cwa - Monsoon with hot summer (orange)

Examples of Arid Climates

BWh - Hot Desert (light yellow on globes); BWk - Cold Desert (greenish yellow); BSh - Hot Steppe (dark yellow); BSk - Cold Steppe (bright yellow)

Urban Heat Island (UHI)

Buildings, concrete, and roads interact with energy Industry, homes, and automobiles produce excess heat City becomes hotter than its surroundings (urban heat island) On this map, urban areas (cities) are warmer than adjacent open space

7.14

CHANGES IN OUR CLIMATE impact many important aspects of our lives, including agricultural food production, sea-level rise, and drought. We use computer models to investigate issues related to climate change. The simplest climate models compute energy (temperature), water, or momentum for a small area over a limited time. The most complicated models use numerical methods and principles of physics to compute atmospheric conditions at many vertical levels across the entire Earth for a long period of time. These are called general circulation models (GCMs). A key issue in climate modeling and prediction is understanding the nature of positive and negative feedbacks in the climate system. A What Are GCMs and How Do They Approach Climate Problems? Modeling Approach 1. As in weather forecasting models, which were explained elsewhere, data are collected from a variety of sources, including aircraft, satellite imagery, balloon launches, and surface stations. 2. Data are quality controlled, to eliminate obvious errors. 3. Equations are run to simulate atmospheric variables at each point for a set time into the future. 4. The "answer" at each grid point becomes the starting point for the next iteration of calculations for another time into the future. 5. After a prediction far enough into the future is generated, the results are scrutinized and plotted on maps. Modeling Procedures 6. The same general data sources are used for climate prediction as for weather forecasting. However, because local-scale weather features can create quite a bit of havoc on short timescales, it is generally more important to have a fner mesh of data for weather forecasting models. Both types of models are generally so complicated that they are run on s... ...geologic time-scales. A critical question involves how the Earth system will respond to such an increase in temperatures. If the warming results in a large amount of melting of ice, the resulting change in albedo can cause even more warming, a positive feedback. If the original warming causes the formation of more low-level clouds, the refective nature of such clouds could be a negative feedback, limiting or even reducing the amount of warming. It is fair to say that if we don't understand feedbacks, it is impossible to model the behavior of Earth's complex climate system accurately. For this reason, much scientifc research has been and currently is investigating the feedbacks that are likely to have the largest infuence on our climate. Scientists are studying the amount of ice in ice sheets and glaciers on land and in sea ice that forms from freezing of the surface of the ocean in polar climates. Some of this research can be done using satellites, but some is done by physically going onto ice-covered regions and observing and measuring what is happening. Atmospheric scientists are using satellites and other methods to measure the amount of water vapor at different levels in the atmosphere, since water vapor is also a greenhouse gas and is much more abundant than CO2. If warming causes an increase in water vapor, the warming will be amplifed, a positive feedback. As we better understand the feedbacks, we will better understand, 1 of 2 04/24/21 and be able to model more accurately, the incredibly complex system that controls our climate. An elegant example of feedbacks and climate is provided by Daisy World (Appendix 7.14Q), which reveals how two different-colored daisies could respond to and affect temperature in an imaginary world.

7.1

CLASSIFICATION IS THE PROCESS of grouping similar items together and separating dissimilar items. Items that are similar in some ways can be different in others, and items that are in different groups can have certain similarities. Classifcations allow us to examine general patterns, with the caveat that interpretations derived from classifed groups are best done cautiously. Here, we examine a well-established method of classifying climates. A What Is the Purpose of Classifying Climates? Climates are classifed to let us observe broad patterns and to simplify communication about the characteristics of a region. Historically there have been thousands of meteorological stations collecting weather and climatic information, and in the past few decades this wealth of knowledge has expanded with the addition of large quantities of remotely sensed information. Classifcation helps us to seek useful generalizations from this enormous amount of information. Climate can be classifed in many ways, with the exact nature of the classifcation depending upon the research question that is of interest. 1. Colors on this map of an imaginary country represent mean annual temperatures (reds above 28°C, blue and purple below 0°C). The black contours represent mean annual precipitation in millimeters. Meteorological stations are shown as dots. Examine the patterns on this map and think about how you might classify different parts of the country (e.g., cold and wet). 07.01.a1 2. The southernmost areas are hot, which is an important fact if we were investigating an outbreak of a heat-related sickness. But we might classify stations in the southeast differently than those in the southwest because of the differences in precipitation (and ther... ...nown as an ecotone. In South America, an ecotone occurs between the Amazon rain forest and mountain climates of the Andes. 3. Köppen's system was designed to delineate vegetation realms, so it overlays well with worldwide natural vegetation zones — biomes. Both climate and vegetation are major controls on the types of soil that develop, leading to a notable similarity between the Köppen classifcation and maps of world soils. These linkages between climate, vegetation, and soils ensure that this classifcation is useful in understanding the physical geography of our continents at planetary and regional scales. More recent satellite data availability over oceans allows us to compute the climate type over the ocean. Köppen was interested in vegetation realms, so he restricted his classifcation to the land.Page 217 C How Is the Köppen Classifcation System Organized? The Köppen climate classifcation system has fve major categories, represented by the frst (capital) letter of the labels on the South America map. These are the following: A - tropical climates, B - arid climates, C - temperate mid-latitude climates, D - harsh mid-latitude climates, and E - polar climates, each represented by a photograph below. The fve categories are further subdivided using a succession of criteria of temperature and the availability of water, as illustrated by the fow chart below. In the A, C, and D climate types, the second letter is lowercase and indicates whether the climate is wet year-round (f), has a dry summer (s), has a dry winter (w), or experiences a monsoon (m). The second letter is uppercase for arid and polar climates. 1 of 2 04/24/21 Subsequent pages list key characteristics of each type of climate, but follow the fow chart below frst.

7.13

CLIMATE CHANGE HAS MANY POTENTIAL IMPACTS, ranging from obvious ones like an increase in global temperatures, to less obvious ones, such as a possible increase in certain diseases. Some consequences are highly probable, whereas others are speculative. On these pages, we briefy introduce some of the most likely results of climate change, specifcally those related to global warming. Abundant information is available elsewhere, including reports by governmental and nongovernmental organizations, if you are interested in following up on this topic. A What Are Some Possible Consequences of Climate Change to the Environment? 1. The fgure below illustrates some consequences of global warming, but many more are possible. Examine the fgure and think about what you know about each feature being depicted and how it might respond to an increase in average temperatures. Then read the text. 2. The most obvious result of global warming would be, well, an increase in global temperatures. However, computer models of climate indicate that many areas, especially those near the poles, will indeed increase in temperature, but other regions might get colder. 07.13.a1 / Source: Cynthia Shaw 3. Higher temperatures would be predicted to cause more melting of snow and ice, resulting in glaciers melting back and becoming less extensive, as has been observed. 4. Higher temperatures and altered ocean circulation could lead to more drought in some places and even the expansion of desert areas, the process of desertifcation. 5. Changes in global temperatures and accompanying changes in precipitation patterns can affect the distribution of communities of plants and animals. In response to warming, such communities may shift to higher elevations or... ...ely, global warming could change vertical wind shear, which might cause tropical cyclones to be more or less severe. What do the actual data say? Frequency of Tropical Cyclones 4. The graph below plots the number of Atlantic storms for each year. The time periods represented on the graph correspond to the interval of time when global temperatures have demonstrably increased (although in detail temperatures have gone up and down during several approximately 30-year cycles). Research using these and similar data suggests that short-lived Atlantic tropical storms may have become more frequent over the years, but moderate-duration storms have not. 07.13.b2 / Source: NOAA 5. The research on this question is ongoing, with more recent evidence pointing to an increased intensity and destructiveness of the strongest storms and less change in weaker storms. Other studies acknowledge that changes in tropical cyclones under climate change scenarios will be small in relation to other factors that create variability in tropical cyclones, such as ENSO. Frequency of Tornadoes 6. Another question to evaluate is whether global warming has caused an increase in the number of tornadoes. Some scientists have proposed that warming provides additional energy that might enhance the environment for such severe storms. Examine the graph below, which plots the number of tornadoes per year during the time when most warming occurred. 1 of 2 04/24/21 07.13.b3 / Source: NOAA 7. The data indicate that the number of strong-to-violent tornadoes in the U.S. has not increased over time. One possible explanation is that increasing surface temperatures would presumably be accompanied by increases in upper-level temperatures, leading to no net change in the number of storms.

7.12

CLIMATE CHANGE IS ALWAYS OCCURRING, including global warming since the mid-1800s. There are many natural causes of climate change, including changes in Earth's orbit around the Sun. Most scientists conclude that human activities, including the burning of fossil fuels and the clearing of forests, contribute to climate change by releasing greenhouse gases, such as CO2, into the atmosphere. Other factors may lead to global cooling, including ash from large volcanic eruptions and an increase in certain aerosols in the atmosphere. Here, we examine some of the factors that can infuence our climate. A What Processes Infuence Atmospheric Temperature Change? Earth's surface temperatures are dominated by energy from the Sun (insolation). Insolation heats the oceans, land, and atmosphere, but several factors infuence how much of this energy reaches the surface and how much is retained. Interaction of Insolation with Earth's Atmosphere, Oceans, and Land 07.12.a1 1. Nearly all of Earth's heating at the surface comes from insolation, which heats the air, land, and oceans. Most of this energy eventually escapes back into space in the form of longwave infrared energy. The rest is delayed by interactions with Earth, keeping the planet warm by the greenhouse effect. The amount of insolation hitting Earth varies regularly, by a small amount, due to orbital fuctuations and changes in the Sun's energy output, as expressed by changes in sunspot activity. Sunspots are the darker areas that, on average, appear and disappear on the surface of the Sun in an 11-year solar cycle. 2. Some insolation is absorbed by the atmosphere (shown as orange disks in the fgure), and some is refected off the atmosphere. Much of the refected insolation retu... ...data from ice cores and tree rings. There have been large variations in the number of sunspots, but most other data suggest that the Sun's energy emission has varied only slightly over the last 2,000 years, so direct warming by the Sun is interpreted to not be the main cause of recent warming. Ocean Oscillations, Climate Change, and Climate Models Recent discoveries have changed our view of the relationship between ocean currents and climate. Studies of the oceans have documented that separate ocean basins (e.g., the Pacifc Ocean) display variations in temperature that occur over years or decades — ocean oscillations. One long-recognized oscillation is the El Niño-La Niña effect and is called the El Niño-Southern Oscillation (ENSO for short). More recently, we have discovered other ocean oscillations, including the Pacifc Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). As their names imply, these oscillations may last decades, whereas ENSO cycles last a year or two. Variations in sea-surface temperatures (SST) and atmospheric pressure can be used to calculate a numerical index for each oscillation, as a way to represent the changes. The graph here shows values for the Atlantic Multidecadal Oscillation (AMO), relative to its long-term average. The AMO represents SST in the Atlantic basin — high numbers indicate warm SST. This graph shows that Atlantic SST undergoes cycles that last several decades. These cycles also relate to periods of abundant or rarer tropical cyclones. They also show some similar patterns to global temperatures, 1 of 2 04/24/21 so because of such correlations, climate scientists are increasingly examining whether oscillations are primarily a cause or an effect of climate change.

7.0

CLIMATE IS THE LONG-TERM PATTERN of weather at a place, including not just the average condition but also the variability and extremes of weather. It is largely controlled by an area's geographic setting, especially latitude, elevation, and position relative to the ocean. Climate is also infuenced by atmospheric pressure and moisture, prevailing and seasonal wind directions, and nearby ocean currents — in other words, everything we have explored so far in this book. Humans also can affect climate by turning open space into cities and by putting CO2 and other gases into the atmosphere. Observed in this context, climate is the culmination of the various factors that move energy, air, and water (in all three states) in Earth's climate system. The climate of a region can be described, measured, and represented in many ways, including maps of annual average temperature and precipitation, like the two globes below (temperature is on the left). To examine long-term climate, as opposed to short-term weather, we consider data averaged over years or decades. Climate is what we expect; weather is what we get. Remember that climate includes not only average values but also extremes and variability about the averages. What is the difference between weather and climate, and how are the two related? Maps of climatic variables, like the ones below, visually represent large amounts of data for the land, sea, or atmosphere. For numerous variables, like temperature and precipitation, maps can depict annual averages, values for a particular month (perhaps the warmest month) as averaged over decades, or some measures of seasonal extremes or variability from one decade to another. What are some regional and global patterns in average tempera... ...dy of water, whether it is the Atlantic and Indian Oceans or the Mediterranean Sea. Evaporation of water in the oceans provides energy for weather systems and other dynamic processes (like fooding), so assessing the climate of the oceans is important in understanding Earth. On land, we consider types of plants in an area when talking about its climate, but how do we assign a climate zone to part of an ocean? The climate of a region is infuenced by many factors discussed in this book, including latitude and its relationship to Sun angle, elevation, topography, the locations of semipermanent pressure features, prevailing wind directions, common storm tracks, sea-surface temperatures, ocean currents, humidity, atmospheric oscillations, and teleconnections. These and other factors act in concert to produce the characteristic climates around the world, such as these in Africa and Europe. How do Sun angle, topography, pressure features, humidity, storm tracks, ocean currents, and other factors interact to produce the observed variations in climate? Climate is not static. Variations happen from year to year, and longer-term changes also occur. Witness the rise of global temperatures in the last 150 years, since the end of a very cold period in the 1800s. Human activities introduce greenhouse gases, such as CO2, into the air, oceans, and land, and these affect our climate. As natural lands or less densely populated areas are converted into cities and towns, long-term averages of temperature, precipitation, cloud cover, and local winds are affected — that is, the extent of urbanization changes the climate. Page 215To what extent are the observed increases in global temperatures during the past century and a half attributable to

Observe the distribution of Tropical Climates (A-type)

Central America and Caribbean (warm pool) Southeast Asia (Vietnam, Cambodia) East of Andes (e.g., Brazil) Central Africa Indonesia, Malaysia, Philippines, Papua Af - Tropical Rain Forest (green); Am - Tropical Monsoon (lavender); Aw - Tropical Savanna (blue-green)

Factors Affecting Climate Change II

Changes in energy from Sun, as either measured directly or estimated from sunspots Changes in Earth's orbit and in tilt of spin axis Ocean oscillations, such as ENSO, Pacific Decadal Oscillation, and North Atlantic Oscillation

Climate Change and Severe Weather

Climate change could affect the frequency or strength of severe storms What do data for the number of tropical cyclones in the Atlantic (top graph) or a number of strong U.S.A. tornadoes (bottom graph) suggest during the time of rising temperatures?

Oceans

Coral reefs are diverse ecosystems that are threatened by increasing ocean temperatures. Acidification of the seawater leads to bleaching, damage and death.

Some Causes of Deserts

Descending Air in Subtropics Cold Ocean Currents Rain Shadow of Mountains Distance from Ocean

Some Causes of Deserts 2

Descending Air in Subtropics Cold Ocean Currents Rain Shadow of Mountains Distance from Ocean

7.3

EACH TYPE OF CLIMATE, as defned by the Köppen climate classifcation, has specifc characteristics that distinguish it from any other climate type. Once a climate is assigned to one of the fve main groups (A-E), it is then categorized by factors such as whether the summer is hot, warm, or cool, and whether most precipitation falls in the summer, winter, throughout the year, or during a monsoon. The table on the following page provides a reference for characteristics of each climate type. Four globes present the same information as the fat map on the previous two pages. Carefully observe each globe, guided by the table, and then read the text blocks in clockwise order around the globes. Click the arrows to learn more Page 221 Table Summary: A table displays common climate types. It is divided into six columns titled frst letter, second letter, third letter, climate type, description name, and description of climate. Common Climate Types First Letter: Climate Group; generally from A near the equator to E near the poles. Second letter generally describes precipitation amounts and seasonality. Lowercase Second Letter (Groups A, C, and D): f = wet year-round; m = monsoon; s = dry summer; w = dry winter Uppercase Second Letter for Group B: S = steppe; W = desert; Uppercase Second Letter for Group E: T = tundra; F = ice cap Third Letter: h = hot; k = cold; a = hot summers; b = warm summers; c = mild summers; d = cool summers First Letter Second Letter Third Letter Climate Type Descriptive Name Description of Climate A Tropical Climates f Af Tropical Rain Forest Generally hot with no cold season; wet year-round m Am Tropical Monsoon Generally hot with no cold season; wet for most of the year w Aw Tropical Savanna or Tropical... 1 of 3 04/24/21 ...12°C (54°F) C Temperate Mid-Latitude Climates f a Cfa Humid Subtropical Wet year-round; long, hot summer and short, intermittent cold season f b Cfb Marine West Coast Wet year-round; warm summer and a cold but not severe winter f c Cfc Marine Mild Summer Wet year-round; mild summer and a cold but not severe winter s a Csa Mediterranean Wet in winter but dry in summer; long, hot summer and short, intermittent cold season s b Csb Mediterranean Wet in winter but dry in summer; warm summer and a cold but not severe winter w a Cwa Temperate Monsoon Wet in summer but dry in winter; long, hot summer and short, intermittent cold season w b Cwb Temperate Monsoon Wet in summer but dry in winter; warm summer and a cold but not severe winter D Harsh Mid-Latitude Climates f a Dfa Humid Continental Wet year-round; hot summer and severe winter f 2 of 3 04/24/21 b Dfb Humid Continental Wet year-round; warm summer and long, severe winter w a Dwa Continental Monsoon Wet in summer but dry in winter; hot summer and severe winter w b Dwb Continental Monsoon Wet in summer but dry in winter; warm summer and long, severe winter f c Dfc Subarctic Wet year-round; short, mild summer and very long, severe winter f d Dfd Subarctic Wet year-round; very short, cool, intermittent summer, and very long, extremely severe winter w c Dwc Subarctic Monsoon Wet in summer but dry in winter; short, mild summer and very long, severe winter w d Dwd Subarctic Monsoon Wet in summer but dry in winter; very short, cool, intermittent summer, and very long, extremely severe winter E Polar Climates T ET Tundra Cold, with no month having an average temperature above 10°C (50°F); freezes occur in every month F EF Ice Cap Cold, with each month having an average temperature below freezing

7.11

EARTH'S CLIMATE HAS CHANGED, both over geologic timescales and in the past 150 - 200 years. The planet has experienced much colder temperatures than today, such as during the Ice Ages, and much warmer ones too, tens of millions of years ago. More recently, we have measured atmospheric temperatures for several centuries, and this record shows an overall increase in temperatures — global warming. What is the evidence that Earth's climate is changing? A What Is the Evidence for Recent Climate Change? Climate change can include global trends in temperature, precipitation, wind directions, and other related measures. Global warming means increasing global atmospheric and oceanic temperatures from some point in the past to the present, and is usually expressed as the temperature compared to the mean global temperature for some time period (e.g., averaged from 1961 to 1990). Scientists examine various records of Earth's climate to investigate past changes, including recent ones. Thermometer Record 1. Thermometers provide a direct measurement of air temperature. These measurements are compared with global temperatures for some reference time to calculate what is called an anomaly (a positive anomaly is warmer than the reference time and a negative anomaly is colder). The graph below plots recent temperatures relative to the reference time period. Most such calculations use a reference time period in the 1980s and 1990s. 07.11.a1 / Source: NOAA/NCDC/NESDIS 2. From these calculations, temperatures were cooler than average (a negative anomaly) in the late 1800s and from the 1940s to the 1970s. Overall, average air temperatures have increased over the last century, especially since the 1970s. Global and U.S. temperatures remain well... ...h creatures provide a proxy for past conditions. This approach provides a long record of climate since we have fossils for millions of years in outcrops and in drill holes into seafoor sediments. 07.11.b6 Ice Core / Source: Heidi Roop, National Science Foundation (NSF)/NASA 6. The accumulation of glacial ice produces seasonal bands that can be counted and measured for stable isotopes in the ice and in trapped bubbles of atmospheric gases. Ice cores from drilling sites in Antarctica and Greenland provide an excellent record of past climate over the past 100,000 years or more. These are important proxies of past temperatures. Weather, Climate, and a Scientifc Approach There is much media attention and controversy about one important aspect of climate change — global warming. As shown on these two pages, evidence for global warming since the mid-1800s is clear. Scientists are always testing, refning, or refuting new, old, or even widely accepted hypotheses — it is part of the scientifc method. One misleading and nonscientifc tactic used by members of the media and others is to point to a specifc weather event, like a single hurricane or tornado, a Midwestern blizzard, or a lack of snow in some region, and say that this proves or disproves, or is a direct consequence of, global warming or the lack thereof. Such short-term events are weather, not climate, and have a complex and still incompletely understood relationship to climate change. The study of climate change is being investigated through the use of complex computer models, developing better strategies to measure temperatures, using these 1 of 2 04/24/21 measurements to determine global trends in temperature, and developing and testing new types of proxies for past temperatures

Flood

Excessive rainfall, hurricane storm surge, and ice melt can cause land areas to flood.

Hurricanes

Extreme events like hurricanes are likely increasing as the global temperature increases.

Forest conservation

Forests, home to some of the most diverse species on the planet, regulate the climate by storing huge amounts of carbon and providing oxygen for life.

Types of Air Pollution

Gases, such as nitrogen oxides Liquid drops in steam and noxious liquids Solid particles, including dust and soot Solid and liquid particles are called aerosols. Aerosols and gaseous pollutants interact with sunlight, so they can decrease air quality and have the potential to influence climate

Observe the distribution of Mid-Latitude Climates (some C- type and D-type)

Great Lakes region, northern Great Plains, S. Canada (Dfa, Dfb) Central Europe and Central Asia (Cfb, Dfb) Tibet, Korea, N. Japan, China (Dwa/Dwb/Dwd) Cfb/Cfc - Marine West Coast (green); Dwd - Subarctic Monsoon (magenta) Dfa/Dfb - Humid Continental (purple); Dwa/Dwb - Continental Monsoon (brown/pink)

Factors Affecting Climate Change

Greenhouse gases, like water vapor and carbon dioxide (CO2), absorb heat radiated from the Earth, warming the planet Human activities have added CO2 into atmosphere from burning forests and fossil fuels Ice cores indicate that temperature and CO2 changed during ice advances and retreats

Average Annual Precip.

Highest rainfall in tropics Low precip. in subtropics and high latitudes

Observe the pattern of climates in Eastern Asia, Australia, and Maritime Asia

Himalaya affect climate patterns Harsh temperate in NE Asia Temperate and arid climates in China Monsoon (temperate) climate in SE Asia Tropical in western Pacific Warm Pool Tropical in SE Asia and adjacent islands Arid in most of Australia; tropical in north Tropical (A) - blue-green; Arid (B) - yellow; Temperate (C) - green; Harsh Mid-Latitude (D) - purple or blue; Polar (E) - gray or white

Average Annual Temp.

Hot in tropics and subtropics Decreasing temperatures toward pole

Controls on High-Latitude Temperatures

Low Sun angle Extreme Variation in Hours of Sunlight, polar reigon has extreme sunlight for a few months then nothing, temperate regions have softer sunlight for longer Summer days with 24 hours of sunlight and winter days with none High Albedo of Snow and Ice (the proportion of the incident light or radiation that is reflected by a surface, typically that of a planet or moon.)

Observe this region and consider how warming temperatures would affect different aspects

Melt snow and ice Increase runoff and decrease salinity of ocean Affect vegetation, perhaps causing desertification or changing CO2 in atmosphere Change evaporation, ocean currents, and oscillations Affect the formation of sea ice, ocean salinity, and thermohaline circulation Change albedo of surface Change amount of clouds, precipitation or severe storms

Ice

Melting glaciers and sea ice contribute to sea level rise, which may inundate islands and coasts.

Observe the pattern of climates in Europe and W. Asia

Mild temperate climates in W. Europe, partly due to Gulf Stream Polar climates at high latitudes Mediterranean (temperate) climate (pink) Harsh temperate climates in eastern Europe and N. Asia, including Russia Mediterranean (temperate) climate (pink) Complex patterns around mountains Arid near Persian Gulf and in Pakistan Tropical (A) - blue-green; Arid (B) - yellow; Temperate (C) - green; Harsh Mid-Latitude (D) - purple or blue; Polar (E) - gray or white

Vital signs

NASA monitors climate change using "vital signs": carbon dioxide, global temperature, Arctic ice minimum, ice sheets and sea level.

7.7

NON-ARID, MID-LATITUDE CLIMATES tend to experience a relatively even distribution of precipitation year-round. Some are dominated by maritime air masses that moderate temperature swings and result in relatively mild winters and summers; they are within Group C in the Köppen designation. Other mid-latitude climates involve more severe winters because they are dominated by continental air masses, and these fall into the D classifcation. Mid-latitude regions are affected by westerlies, and precipitation patterns refect the role of mid-latitude cyclones. A Where Are Marine West Coast and Humid Continental Climates Found? The globes below portray the distributions of three mid-latitude climate types — Marine West Coast climate (Cfb and Cfc), Humid Continental climate (Dfa and Dfb), and Continental Monsoon climate (Dwa and Dwb). Click the slide bar to learn more Examples 07.07.a4 Vancouver, British Columbia / Stephen Reynolds Mid-latitude climates experience long days in summer and short ones in winter. The infuence of the ocean causes marine climates (Cfb and Cfc) to have less seasonality in temperatures than continental ones. 07.07.a5 Parnell Tower, WI / Stephen Reynolds Humid Continental (Dfa and Dfb) climates are wet year-round, but they are farther from any oceanic infuences and so are more seasonal, experiencing hot or warm summers but much colder winters. Table Summary: A table displays four columns contains climate, distance from ocean, and temperature regime. Climate Distance from Ocean Temperature Regime Marine West Coast (warm or mild summer) Immediately downwind of ocean, in mid-latitude westerlies Warm to cool summers, mild winters Humid Continental (hot or warm summer) Far from the moderating infuence of the... ...e polar front jet stream (shown here in idealized form), push maritime polar air masses from the Atlantic deep into the interior of Europe. This is possible in part because south of Scotland, Europe lacks north-south-oriented mountain ranges to confne the relatively warm, damp air to the coastal zones. As a result, most of northwestern Europe has a Marine West Coast climate (Cfb). 07.07.b2 4. The effects of this maritime air fade farther eastward across the continent, allowing continental air masses to exert more control. As a result, countries of eastern Europe, like Belarus and Ukraine, experience Humid Continental climates (Dfb). 5. The east-west oriented Alps often prevent Arctic and polar air masses from reaching southern Europe. Nothing prevents such air masses from penetrating farther southward in eastern Europe, 1 of 2 04/24/21 so the Humid Continental climates extend farther south in that region. Mid-latitude cyclones that occur over these continental-climate areas produce less precipitation than might be expected because of the increased distance from the source of moisture (i.e., the Atlantic Ocean and Mediterranean Sea). Examples: West-to-East Changes Across Eurasia 07.07.b3 / Source: http://www.worldclimate.com/(opens in a new tab) 6. Brussels, Belgium, is very mild for its latitude. This is characteristic of Marine West Coast climates. 07.07.b4 / Source: http://www.worldclimate.com/(opens in a new tab) 7. Kyiv (Kiev) Ukraine, farther east, has a Humid Continental climate (Dfb), with greater temperature variations than Brussels. 07.07.b5 / Source: http://www.worldclimate.com/(opens in a new tab) 8. Seoul, South Korea, has more precipitation seasonality than the Dfb climates because it is affected by the East Asian monsoon

Gaseous Air Pollution Include NOx and SO2

Nitrogen combines with oxygen to form nitrogen oxides (NOx) Concentrations of nitrogen oxides is highest in cities (automobiles)

Observe the pattern of climates in the Americas and adjacent oceans

Patterns more complex on land Polar climates at high latitudes Arid climates in western N. Am. Temperate climates in eastern N. Am. Complex patterns around Andes Antarctica Polar (not shown) Tropical (A) - blue-green; Arid (B) - yellow/tan; Temperate (C) - green; Harsh Mid-Latitude (D) - purple or blue; Polar (E) - gray or white

Carbon footprint

Reducing carbon emissions is a way we can help combat climate change. Businesses and organizations are pledging to reduce energy, reduce waste, and reduce emissions. You can save energy by turning off lights when not in use, keeping the thermostat at a reasonable level, using high-efficiency appliances, and using less hot water. Driving a hybrid or electric vehicle, biking, and planting trees helps reduce emissions. Waste can be reduced by recycling or reusing glass, metal, and plastics. To reduce food waste, make a habit of buying only what you need and not throwing out food. Cutting down on red meat consumption also helps the environment: cattle have a large carbon footprint. Lastly, you can get involved in climate change action groups, and vote on policies that protect the environment.

7.8

SUBPOLAR AND ADJACENT CLIMATES occur at high latitudes in both the Northern and Southern Hemispheres. Climates of polar regions, assigned to Group E in the Köppen system, are extremely cold and are subdivided into Ice Cap (EF) and Tundra climates (ET). Farther from the pole, the Tundra climate gives way to other Group D climates — the Subarctic climate (Dfc, Dfd), and Subarctic Monsoon (Dwc, Dwd) climate. The Subarctic and Group E climates are characterized by frigid temperatures and low precipitation totals. A Where Are Subarctic, Tundra, and Ice Cap Climates Found? Click the slide bar to learn more. B What Causes Low Precipitation Amounts in Subarctic and Polar Climates? 07.08.b1 / Source: http://reynolds.asu.edu/biosphere3d/bio3d_home.htm(opens in a new tab) 1. Polar and adjacent Subarctic climates are characterized by low precipitation, except locally. This is largely because these are cold places, as depicted on this globe of average annual temperatures. Very low temperatures have a number of implications for precipitation. 2. Cold air has a low water vapor capacity, so cold air can carry only limited amounts of water vapor. Without much water vapor, it is diffcult to form clouds and even more diffcult to generate precipitation. Also, much energy goes into latent heat during melting of ice and thawing of upper parts of the soil during the summer, so the surface does not heat up enough to generate convective precipitation. 3. For most of the year, subarctic and polar regions lie far from the zone where warm and cold air masses meet, so frontal precipitation is minimal. Tropical cyclones can never penetrate far enough poleward and inland to infuence Subarctic, Subarctic Monsoon, and polar climates. 4. Another limit... ... 07.08.c5 / Source: NCEP/NCAR Reanalysis dataset 5. Atmospheric Circulation — Strong upper-level westerlies circumnavigate the pole in each hemisphere. Air descending from aloft at the polar high is very cold, ensuring that Arctic and Subarctic climates are cold and dry. Arctic and Antarctic (A) air masses form near the poles and can migrate toward the equator as the westerlies dip equatorward in a trough, as is shown here over the eastern U.S. Examples 07.08.c6 / Source: http://www.worldclimate.com/(opens in a new tab) 6. Notice the extreme continentality in this example of a Subarctic climate in Siberia. These climates have the greatest annual temperature range on Earth (40 C° in this plot). Precipitation is low but peaks distinctly in summer at most sites. 07.08.c7 / Source: http://www.worldclimate.com/(opens in a new tab) 7. Greenland is mostly covered by an ice sheet, but a thin strip of coastal land is exposed. This site, Greenland's capital, is located on a peninsula and is infuenced by relatively warm local ocean currents for its latitude. It gets more precipitation than most other places with a Tundra climate. 07.08.c8 / Source: http://www.worldclimate.com/(opens in a new tab) 8. Found throughout Antarctica, interior Greenland, and the tops of the highest mountains, Ice Cap 1 of 2 04/24/21 climates have unimaginably low temperatures and very low precipitation. This site near the South Pole has never received measurable precipitation. 07.08.c9 Churchill, Canada / Stephen Reynolds 9. Tundra climates also include ice and snow, but they can have unfrozen water during the summer. 07.08.c10 Antarctica / Stephen Reynolds 10. Antarctica is mostly covered by ice, but rocks protrude through the ice in some mountains and along the coast.

Satellite Evidence of Temperature Changes

Satellite measurements also record times of warming, cooling, and little change in temperature Some of these changes correlate with various types of events, such as volcanic eruptions and ENSO

Proxies for Climate Change II

Some proxies involve measuring chemical compositions, such as isotopes, of ancient materials Isotopes of marine fossils, including microscopic ones Isotopes in cave formations Measurements in ice cores

Influences on Precipitation in Warm Temperate Climates

Subtropical highs are weakened by rising air near warm water in western parts of oceans High pressure supported by cool water in eastern parts of oceans, so drier summers (Mediterranean) Bermuda-Azores High has seasonal shifts and variations in strength; weaker in winter, allowing rain in the region High expands and strengthens in summer, leading to dry summers in the Mediterranean Similar shifts for high in S. Atlantic

How Climate and Human Geography Affect Distribution of Pollution

Sunlight can form some types of air pollution, such as ozone; sunny places and concentrated industrial activity and populations result in more ozone Acid rain forms by reaction of atmospheric water with nitrogen and sulfur; acid rain is highest near sites of sulfur emissions (dots), most of which are coal-fired electric plants

7.6

TEMPERATE MID-LATITUDE CLIMATES, designated as Group C of the Köppen system, experience moderate temperatures and precipitation and so are sites of particularly intense human activity. Some temperate climates are relatively warm, because they occur mostly in subtropical latitudes. These include Humid Subtropical, Mediterranean, and Temperate Monsoon climates. A What Is the Spatial Distribution of the Various Temperate Mid-Latitude Climates? The globes below depict distributions of six temperate mid-latitude climate types. These include Humid Subtropical climate (Cfa), two Mediterranean climates characterized by dry summers (Csa and Csb), for which the second letter of "s" represents "summer dry", and three other climates in which precipitation is predominantly in summer due to continental monsoon effects, for which they receive the "w" or "winter dry" designation (Cwa, Cwb, and Cwc). 07.06.a1-a3 / Source: NCEP/NCAR Reanalysis dataset 1. Humid Subtropical climates (Cfa) are wet year-round and have hot summers with relatively short and intermittent cold seasons. They generally occur on the east coasts of continents and adjacent oceans — southeastern South America (shown here), southeastern U.S., eastern Asia (including much of Japan and part of China), and eastern Australia. Since Cfa climates are defned as having hot, rather than warm, summers, their marine extent is somewhat limited. 2. Mediterranean climates experience wet winters but dry and hot (Csa), or dry and warm (Csb), summers. These are pleasant climates for vacationers or retirees. In addition to partly encircling the Mediterranean Sea, they generally occur near the west coasts of continents and in adjacent oceans, including along the Pacifc coast of the U.S.... ...anean climates (in light and dark pink) are more common on the west coasts of continents, but Humid Subtropical climates (shown in light green) are more common along the east coasts of continents — a direct response to the asymmetry of the subtropical highs. 6. With the change in seasons, the Hadley cells migrate toward the opposite hemisphere (e.g., into the Southern Hemisphere during December, the northern winter). The subtropical high in the hemisphere experiencing winter also shifts toward the equator and becomes smaller and less intense, so it no longer blocks migrating weather systems or the southern advance of polar air masses. As a result, frontal precipitation from mid-latitude cyclones spreads across regions of temperate climate during the winter. 7. Thus, a Mediterranean climate owes its characteristic dry and warm or hot summer, but cooler, wet winter, to its subtropical latitude and to the interactions between migrating subtropical highs and ocean currents — a lot of things need to happen for a nice day on a California beach. Examples 07.06.c3 / Source: http://www.worldclimate.com/(opens in a new tab) 8. Athens, Greece, along the northern shore of the Mediterranean, experiences a typical Mediterranean climate, with hot and very dry summers. 07.06.c4 / Source: http://www.worldclimate.com/(opens in a new tab) 9. Taipei, Taiwan, has a Humid Subtropical climate, but winter precipitation is somewhat limited by wind patterns established after the end of the summertime Asian monsoon. 07.06.c5 / Source: http://www.worldclimate.com/(opens in a new tab) 1 of 2 04/24/21 10. Lucknow, India, is in the region affected by the South Asian monsoon, with dramatic variations in rainfall during the year, earning its monsoon designation (Cwa).

7.10

THE CLIMATE OF A PLACE is a combination of the regional atmospheric conditions, such as those expressed by the Köppen climate classifcation, and local effects caused by topography, local wind directions, pollution, and other factors. These result in local variations, commonly called the local climate or the microclimate. The local climate is greatly infuenced by how urbanized the area is. The constructed features of cities and towns infuence how much insolation heats the surface, which in turn heats the air, and how this heat is retained and released. Cities affect their local climate by being warmer than rural areas, especially at night, a phenomenon known as the urban heat island (UHI). A How Do Climate and Human Geography Affect the Distribution of Pollution? Some emitted pollutants react with sunlight, water, or other contaminants to create a new pollutant — a secondary pollutant — that can be more harmful than the original. Climate and physical geography of Earth's surface play a direct role in the degree to which these pollutants are concentrated, but so do the spatial distribution of population density and activities of people, which are part of human geography. Sprawling cities and industrial areas are the largest sources of air pollution in the U.S., where air quality has improved steadily since passage of the original Clean Air Act in 1970. Ozone Pollution 07.10.a1 Sunlight and volatile organic compounds can react with NOx to generate secondary pollutants, including ozone (O3). The same O3 that protects us when it is in the stratosphere is toxic near the ground. It eats away things, such as leaf cuticles and human respiratory tissue. Sunny climates are the most susceptible to O3 pollution, particularly in su... ...developed areas, such as grasslands, forests, and farms. The map was generated mostly using satellite data, including the type of land cover (e.g., concrete and asphalt versus natural vegetation). Can you identify what cities generate the largest UHI? Is there a UHI in the place where you live or go to school? Can you feel a difference between temperatures in the center of the city and those you experience when you travel just outside a city? Other Impacts Associated with Urbanization Urbanization affects local environments in many other ways. In addition to increasing the temperature over the city (UHI), urbanization generally lowers the relative humidity because of higher temperatures and lack of surface water available to be evaporated. An exception to this occurs in some desert cities, like Phoenix, Arizona, where an abundance of irrigation canals, artifcial lakes, golf courses, and watered lawns can raise humidities compared to the surrounding desert — an oasis effect. Urbanization can also change wind speeds and directions. Wind speeds are generally lower in cities because buildings block winds and provide friction that slows the wind. Winds can be stronger locally if they blow parallel to streets, allowing them to be channeled between buildings, in what is called an urban canyon. Since urbanization modulates temperature and pressure, it can also affect the amounts and 1 of 2 04/24/21 spatial distribution of precipitation. For example, precipitation is generally greater downwind of a city because abundant particulates introduced into the air by urban activities provide nuclei for condensation. Fog can be reduced in cities by changes in temperature and humidity, but smog, which is related to pollution, is concentrated near cities.

7.2

THE KÖPPEN CLIMATE CLASSIFICATION was defned for land areas and generally is depicted as a map portraying regional or global distributions of different climate types. The map on these two pages covers the entire planet and is an Extended Köppen Climate Classifcation, because we have extended the land-defned Köppen classifcation to encompass similar climatic conditions over the oceans. This allows us to better explore how different climates relate to regional atmospheric features, like high pressure in the subtropics. Note that this type of world map exaggerates the size of high-latitude regions. Study the patterns of different climates at this scale of the entire planet and then focus on a single continent or part of a continent. Refer to following tables for a key to the labels. What is the label for the place where you live?Page 219 07.02.a1 Table Summary: A table displays main climate groups with examples from west to east. The climate groups are Tropical, Arid, Temperate Mid-Latitude, Harsh Mid-Latitude, and Polar. Group Letter Name Examples (West to East) A Tropical Central America, Caribbean, Amazon, Congo, Indonesia B Arid Southwest U.S., Sahara, Arabia, Tibet, central Australia C Temperate Mid-Latitude Southeast U.S., NE Argentina, Mediterranean basin, Japan D Harsh Mid-Latitude Southern Canada, northeastern Europe, Siberia E Polar Northern Alaska, Arctic, Greenland, Antarctica

Observe the pattern of climates in Africa

Temperate climates around the Mediterranea Arid climates in Arabia Arid climates in Sahara and Sahel Complex patterns around Great Rift Tropical near Equator, especially in Congo Basin Temperate climates in south-central Africa Arid climates in southwest Africa Tropical (A) - blue-green; Arid (B) - yellow; Temperate (C) - green; Harsh mid-latitude (D) - purple or blue; Polar (E) - gray or white

Implications of Climate Change

The computer-generated images below depict the decrease in sea ice in the Arctic between 1979 (left globe) and 2015 (right globe), while the planet was warming Melting of sea ice does not affect sea levels but does decrease the albedo of the surface, habitats of arctic creatures, and the salinity of underlying sea water (which can affect the thermohaline circulation)

Feedbacks in the Climate System: Water Vapor and Clouds

Warming of water bodies causes more evaporation, increasing the amount of water vapor, a greenhouse gas (a positive feedback) Warming of water bodies causes more evaporation and water vapor, forming more low-level clouds that reflect sunlight, causing cooling (a negative feedback)

Proxies for Climate Change

We use other types of data, called proxies, to reconstruct temperature before thermometers existed Length of glaciers Fossils of plants and animals Measurements of tree rings

Observe the distribution of Warm Temperate (C) Climates

West Coast and Southeastern U.S Mediterranean China Southern S. Am. Southern Africa Coastal Australia Cfa - Humid Subtropical (light green); Csa/Csb - Mediterranean (pink/ green); Cwa/Cwb/Cwc - Monsoon (orange/light orange/gray)

Observe the distribution of Tropical Climates (B-type)

Western U.S. and Mexico Sahara (BWh) and Sahel (BSh) Cold steppes and deserts of central Asia S. Am. Deserts and cold steppes Southern Africa Asia Australia BWh - Hot Desert (light yellow); BWk - Cold Desert (greenish yellow); BSh - Hot Steppe (dark yellow); BSk - Cold Steppe (bright yellow)

What is the cause of most deforestation?

agricultural expansion

The atmosphere undergoes more heating

as more greenhouse gases are added to the air

A change in the global average temperature is not something we can easily "sense",

as some regions warm faster than others, and some regions even cool as weather patterns shift.

Precipitation in Mid-Latitude Climates

Within belt of westerlies, so experience mid-latitude cyclones and precipitation throughout year Westerlies and polar front jet stream push storms into Europe, so Marine West Coast Climate Effect of moist air fades to east, so change to Humid Continental

When fossil fuels are burned, however,

a huge amount of carbon is released into the air, adding to the greenhouse effect.

Since the industrial revolution

a new and alarming trend has emerged.