Meteorology Final Exam SMU

Conventional Radar

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Doppler Radar

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What is a "time step" in a numerical weather prediction model?

A forecast of how the weather will change over a short time period, NWP computer model assesses and then projects the CURRENT state of the atmosphere to some time in the future using time steps. Time steps of 5-10 mins are common. Keep doing this and you'll get a two week forecast.

Particulate Matter (PM)

A mixture of solid particles and liquid droplets found in the air.

Air Quality Index (AQI)

A standardized indicator for reporting daily air quality to the general public. Provides info on health effects people may experience within a few hours or days of breathing polluted air. EPA calculates AQI for Five major pollutants regulated by the Clean Air Act: Ground-Level Ozone* Particulate Matter* Carbon Monoxide Sulfur Dioxide Nitrogen Dioxide *Greatest risk to human health in the US. AQI Scale runs from 0 to 500 : The higher the value, the greater the level of air pollution Values below 100 - Considered Satisfactory Values above 100 - Considered Unhealthy - First for sensitive groups and as the value increases, for everyone else.

Volatile Organic Compounds (VOC)

A wide array of solid, liquid, and gaseous substances that are composed exclusively of hydrogen and carbon. Also called Hydrocarbons. CH4 (methane) is most common but is generally harmless. Mainly caused by the incomplete burning of gasoline in motor vehicles.

Climates A,B,C,D,E: Main characteristics of each

A) Humid Tropical - Winterless climates - All months have a mean temperature above 18C (64F) B) Dry - Evaporation exceeds precipitation - There is a constant water deficiency C) Humid Middle-Latitude (Mild Winters) - Average temperature of the coldest month is below 18C (64F) but above -3C (27F) D) Humid Middle-Latitude (Severe Winters) - Average temperature of the coldest month is -3C (27F) - Average temperature of the warmest month exceeds 10C (50F) E) Polar - Summerless climates - The average temperature of the warmest month is blew 10C (50F)

Dry Deposition

Acid-producing chemicals in drier climates with limited precipitation may become incorporated into airborne dust or smoke and then fall to the ground. When it actually does rain, these acids are carried off into rivers and streams making them more acidic

Aerosols: Impact on global climate. Which aerosol actually contributes to global warming and not global cooling like most aerosols do? Why does it do this?

Aerosols are tiny, liquid and solid particles that are suspended in the air. Natural sources include wildfires, dust storms, breaking waves, and volcanoes. Most human-generated aerosols come from the combustion of fossil fuels and burning vegetation. Most aerosols reflect solar radiation back into space leading to a cooling effect which in turn tries to lessen the effect of greenhouse gas warming. The extent at which the aerosol cooling effect offsets the greenhouse gas warming effect is UNCERTAIN.

Smog

Air pollution in urban and industrial areas (smoke & fog).

Warm Front

As the warm air meets with the cool air, the warm air usually glides up and over the cool air GENTLY forming light to moderate precipitation. If the atmosphere is unstable, then heavy thunderstorms can form as the warm air is forced to rise (summer). Note that the precipitation that forms with a warm front always falls into cooler air. This is why snow, freezing rain and sleet are often associated with warm fronts. Light-to-moderate rain, snow, freezing rain in the winter Heavy rain possible in the summer.

Humans: Air, Food & Water

Average adult requires 30 lbs of air each day compared to 2.6 lbs of food and 4.4 lbs of water.

Oxygen Isotope Analysis: How does it tell if the earth was colder or warmer than normal in the past?

Based on precise measurements of the ratio between two isotopes of oxygen (16O | 18O). There is more 18O in ocean water during glacial (cold) times. There is more 16O in ocean water during interglacial (warmer) times. Water (H2O) - can form with either16O or 18O. Water composed of 16O evaporates more efficiently from the ocean than 18O, especially when temperatures are cold. Thus when global temperatures are cold, ocean water has a higher 18O content since the 16O evaporates more easily. BUT ... the rain and snow that falls from clouds created by this evaporated 16O water during times of colder-than-normal weather conditions has a much higher 16O content. The ratio of 18O to 16O in precipitation is very small when the world is colder. The ratio of 18O to 16O in precipitation is larger when the world is warmer. The opposite would be true for ocean water.

Analog

Based on the assumption that weather repeats itself. Forecasters find weather patterns from the past that are similar to a current event (current conditions). Pattern recognition is an important tool, helps improved short-range, computer generated forecast.

Milankovitch Cycle

Based on the premise that variations in incoming solar radiation are a principal factor controlling Earth's climate.

Black Soot

Black carbon is soot generated by combustion processes. Black Soot behaves differently from most other aerosols. Increases atmospheric temperatures due to its low albedo, and thus it absorbs rather than reflects incoming solar radiation.

Greenhouse Gases

CO2, CH4, CFC, Nitrogen Oxides, Water Vapor

Obliquity

Changes in the angle of the Earth's axis.

Volcanic Activity

Changes the reflectivity (albedo) of the Earth as well as the composition of the gases in the Earth's atmosphere. Explosive eruptions emit huge quantities of gases and fine grained debris into the atmosphere. Greatest eruptions can inject material high into the stratosphere where it spreads around the globe and remains for many months or years. Suspended volcanic material will filter out a portion of the incoming solar radiation which will lower the temp of the troposphere.

Positive and Negative Feedback Mechanisms - What are they, and how can water vapor contribute to both?

Climate Feedback Mechanism - Several different possible outcomes that may result when one of the atmospheric system's elements is altered. Positive Feedback Mechanism: Any effect that acts to reinforce an initial change. Negative Feedback Mechanism: Any effect that is opposite to the initial change and tends to offset it.

Water Vapor & Feedback

Clouds are a negative feedback mechanism as they increase the Earth's albedo and diminish the amount of solar energy available to heat the atmosphere. Clouds are a positive feedback mechanism as they absorb and emit radiation that would otherwise be lost from the troposphere.

Coarse Particles

Coarse particles are defined as being larger than 2.5 micrometers in diameter. Come from dirt roads, materials handling, windblown dust, crushing/grinding [Primary Pollutant].

Ocean Currents

Cold currents cause dry conditions (aridity) and frequent fog formation. Warm currents cause warmer air temperatures and more precipitation.

Prognostic Maps

Computer-generated forecast showing the expected pressure pattern at a specific future time.

Atmospheric Stability

Determines the extent to which vertical motions will mix the pollution with cleaner air above.

Trend

Determines the speed and direction of features such as fronts, clouds, and precipitation (cyclones, showers, thunderstorms) and using this data, forecasters try to extrapolate the future position of weather phenomena using what the entities are doing now. Most effective for periods of just a few hours.

Inversions Aloft

Develop in association with the sinking air that characterizes centers of high air pressure (anticyclones) .

Subsidence Inversion

Develops aloft between the lower turbulent zone and the subsiding warmer layers above.

The Koppen Classification

Devised by Wladimir Koppen (German climatologist). Best known and most used system for general world pattern of climates. Uses easily obtained data (mean monthly & annual values of temp and precipitation). Criteria are unambiguous and simple to apply. It divides the world into climate regions in realistic way. Koppen believed distribution of natural vegetation was best expression of overall climate.

Global Warming

Due to the complex interactions between the atmosphere and the land and the sea, some parts of the world are actually getting colder. Warmer than normal air over the Antarctic can lead to more water vapor allowed in the atmosphere which can lead to heavier-than-normal snowfall which can in turn lead to an increase in ice sheets. The warming of the air in arctic latitudes is melting sea ice which has been known IN THE PAST to alter ocean currents which can lead to severe cooling - even a mini Ice Age - in parts of Europe.

Fine Particles

Fine particles are defined as being less than 2.5 micrometers in diameter. Come from motor vehicles, power generation, industrial facilities, fireplaces.

Latitude

Fluctuations in the amount of solar radiation received at Earth's surface are the single greatest cause of temperature differences.

Economic Impact of Meteorological Topics

Heating Degree Days (HDD) and Cooling Degree Days (CDD) Water Balance Analysis Water balance determines whether or not crops can survive

Temperature & Pollution

High temperatures promote efficient chemical reactions which can also enhance secondary pollutant formation. But low temperatures can also promote secondary pollutant formation by allowing gaseous emissions to condense into particulates.

Mountains and Highlands

If the prevailing winds are west to east then a north-south mountain range would act like a barrier to this wind flow. Orographic lifting creates heavy rain on the windward side, but a rain shadow desert on the leeward side of mountains. Locations near the windward side of a continent would nevertheless have more of a continental climate if a mountain barrier blocks the sea to land wind flow.

Proxy Data

Indirect evidence that comes from natural recorders of climate variability. sea floor sediments glacial ice fossil pollen tree growth rings historical documents Scientists who analyze proxy data and reconstruct past climates are engaged in Paleoclimatology. Main Goal: Understand the climate of the past in order to assess the current and potential future climate.

Ensemble

Involves producing a number of forecasts using the same computer model but slightly altering the initial conditions, while remaining within an error range of the observational instrument.

Subtropical Jet Stream

Is a semi-permanent jet stream over the subtropics. It is a west-to-east current, centered at 25° N and S. It is mainly a winter phenomenon. Why? Because in the summer there is not much of a temperature difference between the tropics and the mid-latitudes. The subtropical jet stream is slower than the polar. Becomes a major player during El Nino.

Nowcasting

Is a type of trend forecasting that is used to predict very short-lived localized weather events. Depends on Geostationary satellites.

Polar Jet Stream

Is strongest and most prevalent. It occurs along a major frontal zone, called the polar front. But moves when temperatures contrasts move north and south. The jet stream moves faster in winter because of bigger temperature contrast from Equator to Pole. During the summer, jet stream shifts north and takes severe weather threat with it.

Effects of Acid Precipitation

It lowers the natural pH of lakes and rivers turning them into acid lakes and streams. It reduces agriculture yields since many plants are very sensitive to the acidity of their soil. It corrodes metals and stone structures by dissolving the material they are made of.

Clean Air Act of 1970

It was responsible for the creation of the Environmental Protection Agency. Set standards for the four primary pollutants (thought to be the most objectionable) as well as one secondary pollutant. These are called the CRITERIA POLLUTANTS. Primary: Particulates Sulfur Dioxide (SO2) Nitrogen Dioxide (NOX) Carbon Monoxide (CO) (Eventually LEAD (Pb) was added to this list.) Secondary: Ozone

Controls of Climate

Latitude Land and Water Geographic Positioning and Prevailing Winds Mountains and Highlands Ocean Currents and Wind Systems

Pressure and Wind Systems

Latitudinal shifting of "pressure belts" is responsible for seasonal precipitation. Low pressure "belts" encourage precipitation - Equatorial region - Midlatitudes High pressure "belts" discourage precipitation - Subtropical region - Polar regions

Polar-Orbiting (POES)

Low flying satellites that orbit over the poles. Records images of the entire planet twice daily.

Sunspots and Temperature

Low sunspot activity is associated with colder periods in North America and Europe but relationship has not been fully confirmed.

Ancient Sea Creatures

Make their shells out of Calcium Carbonate (CaCO3) take oxygen out of the ocean water to make CaCO3. Some of the oxygen is 16O, and some of it is 18O. If global temperatures are cold, then more of their shells will be made with 18O since the 16O tends to evaporate more readily. Thus, the 18O/ 16O ratio is relatively large if global temperatures are warmer, then the 18O/ 16O ratio is not quite as big.

Land and Water

Marine Climates - relatively mild for their latitude since water moderates temp. Continental Climates - tend to have much more extreme annual temp fluctuations.

Role of Trace Gases

Methane (CH4) primarily from massive cattle feedlots as well as swamps, wetlands, and rice cultivation. Nitrous oxide (N4O) primarily from automobile exhaust and byproducts of agriculture activity and the use of fertilizers Chlorofluorocarbons (manmade CFCs) all absorb wavelengths of outgoing radiation from Earth and are effective greenhouse gases. Thus CO2 is NOT the only contributor to greenhouse warming.

Global Impact of Meteorological Topics

Montreal Protocol CO2 and Global Warming, 3 consequences of Global Warming Nations/World Governments sharing data (why and two examples)

Plate Tectonics

Movement of the Earth's continents towards and away from low latitudes to higher latitudes and vice versa.

Water Vapor Images

Obtained by satellites equipped with detectors designed to pick up radiation emitted by water vapor. Most of Earth's radiation at 6.7mm is emitted by water vapor. These satellites map the concentration of water vapor in the atmosphere. Bright (white) areas: high water vapor, Dark: drier air (low water vapor).

Infrared Images

Obtained from radiation emitted from objects. Produced by computers programmed to display: warm objects in black, colder objects in white. Useful in determining which clouds are most likely to produce precipitation as the clouds that usually produce the most precipitation appear very bright.

Why is latitude the main control for climate?

Of all the "controls" of climate, this is THE MOST IMPORTANT ONE because latitude mostly determines the amount of solar radiation received, and thus it mainly determines temperature. Locations on the same latitude circle have identical sun angles and hours of daylight. Tropics: sun angle is always high at noon, the temperatures are always warm. Poles: sun angle is always low (or less than zero), so it is always cool in polar areas.

Inhalable

Particles that are less than 10 microns in diameter (i.e., both fine and coarse). Once inhaled they can cause serious health effects such as asthma as well as heart and lung disease.

Sunspots and Drought

Periods of drought in western US coincide with 22-year magnetic cycle of the Sun.

Photochemical

Photochemical Reactions are chemical reactions triggered by strong sunlight. Nitrogen oxides (primary pollutant) absorb sunlight in the presence of VOCs and produce secondary pollutants. NOx and VOCs produce a noxious mixture of gases and particulates which can be highly irritating to the lungs and can damage vegetation. Collectively, this noxious mixture is called "photochemical smog". The major component in this mixture is Ozone.

Natural Causes of Climate Change

Plate tectonics, volcanoes, eccentricity, precession, obliquity, Solar output, Sunspots

Chronic

Pollutant levels cause gradual deterioration of a variety of physiological functions over a span of years.

Acute

Pollutant levels that may be life-threatening within hours or days.

Secondary Pollutants

Produced in the atmosphere when certain chemical reactions take place among primary pollutants. In some cases, effects of primary pollutants are less severe than the effects one the secondary pollutants they form.

Visible Light Images

Records the intensity of light reflected from cloud tops and other surfaces. Black and White Image: Bright areas are areas that are strong reflectors of light (clouds, snow), Gray areas reflect less light than clouds (land), Black areas reflect little light (oceans). Useful in identifying cloud shape, the higher its albedo, the brighter it appears.

Geostationary (GOES)

Satellites that orbit west to east over the equator. Remain fixed over a point on Earth as their rate of travel keeps pace with the Earth's rotation. Images less detailed.

Cold Front

Showers and storms associated with cold fronts are almost always more intense than those associated with warm fronts whose slope is more gentle and don't move as fast. Rain or snow in the winter Thunderstorms in summer.

How does the sinking air (subsidence) associated with subtropical highs affect a region's climate?

Sinking air leads to a stable atmosphere which prevents precipitation and thus leads to a drier climate

Temperature Inversions

Situations in which the atmosphere is very stable and mixing depths are significantly restricted. Warm air overlying cooler air acts as a lid and prevents upwards movement, leaving the pollutants trapped in a relatively narrow zone near the ground.

Sunlight & Pollution

Strong solar radiation can cause photochemical reactions in the atmosphere to produce secondary pollutants.

VOG: Volcanic Smog

Sulfur Dioxide combines with Oxygen + Water Vapor in presence of Sunlight. Reduces visibility, Aggravates respiratory problems.

Solar Variability

Sunspots are huge magnetic storms on the Sun's surface. They eject large numbers of particles that interact with gases in the Earth's upper atmosphere. They are on approximately an 11-year cycle between high and low activity.

Variations in Earth's Orbit

The Milankovitch mathematical model is based on several ways the motion of the Earth can affect global climate. Alters the Earth-Sun relationships. Eccentricity (shape), Obliquity (angle), Precession (wobble).

How does the migration of the ITCZ affect climate in the tropics?

The Tropical Monsoon Climate (Am) is characterized by the changing position of the ITCZ - Intertropical Convergence Zone. The ITCZ follows the sun's direct rays, and thus it migrates back and forth across the Equator. Thus, a dry spell occurs in winter.

Climate Classification: Who were the first to attempt this? Who created the modern climate classification scheme, and what de he use to define a location's climate?

The ancient Greeks were the first to attempt climate classification. They divided each hemisphere into three zones: torrid, temperate, frigid. The basis was Earth-Sun relationships.

Acid Rain

The burning of large quantities of fossil fuels (mainly oil and coal) releases millions of tons of sulfur and nitrogen oxides (NOx gases) into the atmosphere. Through complex chemical reactions, some of these pollutants are converted to sulfuric and nitric acids. The acids mix with rain or snow and fall to the Earth's surface as acid precipitation.

What is the pH scale, and how does it measure the acidity or alkalinity of a substance such as rainwater?

The pH scale measures the degree of acidity or alkalinity of a solution. The Lower the number, the more acidic a substance is. Each whole number indicates a tenfold difference. Unpolluted rain water has a pH of about 5.

Persistence

The technique based on the tendency of weather to remain unchanged for hours of days (least accurate method).

Climatological

This method uses climate data, or average weather statistics over many years (usually 30). Usually not a very accurate forecast since weather rarely agrees perfectly with climate, but sometimes only method when predicting months in advance.

Wet Deposition

Through a series of chemical reactions, pollutants emitted from sources such as power-generating plants, ore-smelting, petroleum refining and motor vehicles of all kinds, are converted to acids in the atmosphere that get incorporated into clouds that go on to produce acidic rain or snow.

Mixing Depth

Vertical distance between Earth's surface and the height to which convectional movements (rising air bubbles) extend. The Greater the Mixing Depth, the better the air quality. When air is stable, there is little convection and the mixing depths are small. Pollution gets concentrated. When air is unstable, there is greater convection and the mixing depths are large. Pollution gets dispersed.

Societal Impact of Meteorological Topics

Weather modification (Three Methods) Cloud seeding Frost Prevention Hail Suppression Sulfur Dioxide in Rain Clouds Clean Air Act of 1970

What does it mean to be a "dry" climate? Why are polar areas not considered dry even though very little precipitation occurs there?

What is meant by the term "dry"? Yearly precipitation is less than the potential water loss by evaporation. The dryness of an area is not only related to its rainfall but also to the amount of evaporation that occurs. The hotter the temperatures, the more the evaporation takes place. Most B climates are created by subtropical highs, subsidence.

Wind & Pollution

When winds are weak, pollution is worse because it gets concentrated over any given area. When winds are strong, pollution is seldom a problem due to the wide dispersion of pollutants.

Geographic Positioning and Prevailing Winds

Windward sides of continents (prevailing winds coming from the sea to land) are likely to have marine climates. Leeward sides of continents (prevailing winds coming from the land to the sea) are likely to have continental climates.

Jet Streams

"Rivers" of fast moving air in the upper-levels of the atmosphere (near tropopause) embedded in the westerlies. Polar and subtropical jet streams.

Where do the largest differences in annual temperatures occur and why? Why do annual temperatures not change very much in the tropics?

At higher latitudes because the sun light is more direct in the summer and less direct in the winter whereas at the tropics they receive direct sunlight year round.

Synoptic Maps

Describes the state of the atmosphere over a large are at a given time (temperature, humidity, pressure, wind).

Primary Pollutants

Emitted directly from identifiable sources. They pollute the air immediately upon being emitted

Rising CO2 Levels

Energy leaving the Earth - in an attempt to cool the Earth down - is intercepted by CO2 (and a few others) and re-emitted back to the Earth keeping it warmer than it would otherwise be. Without this greenhouse effect, the average temperature of the Earth would be around 0°F instead of the 59°F it is today.

Surface Temperature Inversions

Form because the ground is a more effective radiator than the air above.

Knowledge of Emerging Technologies in Meteorology

How are hurricanes monitored and tracked? Satellites, aircraft, radar (VORTRAC), data buoys. General Circulation Models (GCM) , Human responsibility for Global Warming.

Precession

The "wobbling" of Earth's axis.

Eccentricity

Variations in shape of Earth's orbit about the Sun.