APES Chapter 4: Global Climates and Biomes
ENSO Consequences
- Suppresses upwelling of South American Coast witch decreasing productivity and fish pop - Effects world, Ex. cooler and wetter condition in SE USA, dry weather in S. Africa and SE Asia.
Variation in amount of SA over which the Sun's rays are distributed
- The angle w/ which the sun hits a particular region of Earth changes throughout the year. The smaller the angle, the less surface area sunlight hits, this means the solar energy is more concentrated. The larger the angle, the less SA, and the more scatted the solar energy is.
3 Causes of Uneven Warming on Earth
1. Angle Sun's rays hit Earth 2. Variation in amount of SA over which the Sun's rays are distributed 3. Albedo
4 Properties that determine how air currents circulate
1. Density 2. Water Vapor Capacity 3. Adiabatic Heating and Cooling 4. Latent Heat Release
Convection Currents Diagram
1. Hot dry air picks up moisture as it moves along the land's surface 2. Humid air at the Earth's surface warms and rises 3. Adiabatic cooling causes air to reach saturation point 4. Condensation forms clouds and precipitation 5. Laten heat release from condensations causes air to expand and rise 6. Adiabatic cooling chills the air at the top of the troposphere 7. Cold dry air is displaced horizontally and sinks back to Earth's surface 8. Adiabatic heating warms dry air that sinks to Earth's surface.
Mesosphere
3rd layer of atm. Around 35km
Thermosphere
4th and largest layer of the atmosphere. Block harmful x-ray and UV radiation from reaching the planet. Contains charged gas molecules that glow and produce light when hit by solar energy. It is driven by magnetic forces of the North and South pole creating the Aurora Borealis (N) and the Aurora Australis (S)
Exosphere
5th and outer layer of the atmosphere. Extends out into space. The gas in this layer are so spread out that this is very little to no pressure.
Regions of Earth (relative to the equator)
90°N = North Pole (shrinks + expand depending on warmer/colder season) 60°-30°N = Subtropic Region (can find deserts) 30°N = Tropic of Cancer EQUATOR - Tropical Region falls between 30°N and 30°S (find ice covered mountain peaks) 30°S = Tropic of Capricorn 60°-30°S = Subtropic Region 90°S = South Pole
La Nina
A cooling of the ocean surface off the wester coast of South America, occurring periodically every 4-12yrs and affecting the Pacific and other weather patters. Cold counterpart of El Nino. Essentially, surface water in the pacific is colder than usual.
4 Properties that determine how air currents circulate: Adiabatic Heating & Cooling
Adiabatic Cooling = cooling effect of reduced pressure on air as it rises in the atm. and expands till it reaches its dew point (before cooling and condensing again) Adiabatic Heating = heating effect of increased pressure on air as it sinks toward Earth's surface and decreases in volume. Warm air rises, and as it does so it undergoes a change in air pressure (density) causing it to expand and cool (think of breaking up food on your plate). As the air cools in begins to sink, getting denser and denser warming and picking up moisture as it moves.
Why does warm air rise?
Air molecules break apart due to solar E. The heat is released with more space to expand. The point at which air releases heat is called the latent point.
Why does Earth experience seasonal changes in climate?
Because Earth's axis of rotation is tilted 23.5 degrees, Earth's orbit around the sun causes most regions worldwide to experience seasonal changes in temperature and precipitation.
Ferrell cells
Convection current in the atm that lies btwn the Hadley and Polar cells. Does not form as distinct convection cells, but are driven by circulation of Hadley and Polar cells. This helps to distribute warm air away from the tropics and cold air from the poles. Causes a range of warm and cold air currents to circulate between 30° and 60°
Coriolis Effect
Deflection of object's path due to Earth's rotation. The deflection of objects moving N. or S. occurs because the planet's surface moves faster at the equator than at a high latitude. For example, a ball is thrown from the N. Pole toward the equator would be deflected to the West by the Coriolis Effect. Different rotating speeds of Earth at different latitudes causes a deflection in paths of travelling objects.
Rainshadow effect
Dry region formed on leeward side of a mountain as a result of humid winds from the ocean that cause precipitation on the windward side. Humid winds blow in land from the ocean and meet a mount range. On the windward side of the mountain, air rises and cools and large amount of water vapor condense to form clouds and rain. On the leeward side of the mountain, cold, dry air descends, warms via adiabatic heating causing much drier conditions
How do gyres redistribute heat in the ocean?
Gyres redistribute heat in the ocean: - Cold water from polar regions move along the west coasts of continents and cool air above these waters brings cooler temps to these continents. - Warm water from the tropics moves along the East coast of continents and warm air above the water brings warmer temperatures to land.
Global Wind Currents
Hadley, Ferrell, and Polar Cells
El Nino Southern Oscillation (ENSO)
In a normal year, trade winds push warm surface waters away from the coast of South America and promote upwelling of water from the ocean bottom. Every 3-7yrs, trade winds weaken or reverse direction so warm waters build up along the west coast of Peru causing equatorial water from the west pacific to move east toward the West Coast of South America. This suppresses upwelling off the coast of Peru. (Overall, warmer than normal in the South)
Gyres
Large-scale pattern of water circulation that moves clockwise @ the Northern Hemi and counterclockwise @ the Southern Hemi. Water moves straight along the equator, then hits a land mass creating a cycle.
Intertropical Convergence Zone (ITCZ)
Latitude that receives the most intense sunlight, which causes ascending branches of 2 Hadley Cells to converge. Typified by dense clouds and thunderstorm activity. The lat of ITCZ is not fixed due to Earth's angle.
troposphere
Layer of atm closest to Earth's surface, extending approx 16km (10mi) Densest layer Circulates liquids and gases; where most of atmospheric Nitrogen, Oxygen, and water vapor occur. Where Earth's weather occurs.
What layers of earth atmosphere have higher mass of air; What layers of Earth have higher air pressure (Why?); Air temp relative to distance from Earth's surface
Layers closest to Earth have a higher mass than air about them. Layers closer to earth have higher air pressure because the molecules are more densely packed. Air temp decreases w/ distance from Earth's surface and with latitude.
4 Properties that determine how air currents circulate: DENSITY
Mass of all molecules in the air in a given volume Determines movement of air currents: less dense air rises (warm air), more dense air sinks (cold air)
December solstice
Northern Hemisphere is at its max tilt AWAY from the sun resulting in the SHORTEST day of the year.
June Solstice
Northern Hemisphere is at its max tilt TOWARD the sun resulting in the LONGEST day of the year
What are ocean currents are driven by?
Ocean currents are driven by - Temperature - Gravity (G) - Prevailing Winds - Coriolis Effect - Salinity - Location of continents
Why is the flow of ocean water important/ affect global climates?
Ocean currents move warm and cold water around the globe affecting primary productivity in different ocean regions in addition to the climates of the adjacent continents.
Easterlies
Polar winds come out of the northeast in the N. Hemisphere and the southeast in the S. Hemisphere.
Westerlies
Prevailing winds above 30° located in the S. Hemisphere coming from the southwest. Westerlies are also located 30° in the Northern Hemisphere coming from the northwest.
Northeast and Southeast Trade Winds
Prevailing winds produced by Hadley cell northeast and southeast of the equator. Wind, in general, moves opposite direction the Earth is moving.
Angle Sun's rays hit Earth
Region closest to the equator is stuck by the sun's rays at a 90degree angle. At mid-latitude and polar regions, the sun strikes at oblique angles. The more oblique the angle of the sun's rays the more solar energy is lost as it passes through the atmosphere. More solar E reaches the equator than mid-lat and polar regions
4 Properties that determine how air currents circulate: Latent Heat Release
Release of E when water vapor in the atm condenses into liquid water (release of heat when water changes from vapor to liquid). Whenever water vapor in the atm. condenses, air warms and rises.
Saturation Point
Saturation point is the max amount of water vapor that can be in the air at a given temperature.
March (vernal) and September (autumnal) Equinox
Sun is directly overhead at the equator and all regions of Earth receive 12hrs of daylight 12hrs of darkness. Each pole is EQUIDISTANT from the sun.
What keeps layers of gas that make up earth's atmosphere in place?
The pull of gravity on gas molecules keeps layers of gas that make up earth's atmosphere in place
Layers of the atmosphere (Closest-Farthest from Earth's surface)
Troposphere Stratosphere Mesosphere Thermosphere Exosphere
4 Properties that determine how air currents circulate: WATER VAPOR CAPACITY
When temperature falls, the saturation point decreases, this means that the water vapor will condense turning into liquid water, forming clouds then rain.
Polar Cells
convection current in the atm forced by air that rises at 60°N and 60°S and sinks at the poles.
Hadley Cell
convection current in the atm that cycles btwn the equator and 30°N and 30°S. It is driven by the intense solar E that hits Earth near the equator. 1. Solar E warms humid air in the tropics 2. Warm air rises and cools below its saturation point 3. The dry air sinks to Earth's surface approx 30°N and 30°S. 4. As the air descends it is warmed by adiabatic heating. This forms deserts and those latitudes.
Atmospheric convection currents
global patterns of air movement initiated by the unequal heating of Earth.
Stratosphere
layer above troposphere, extending roughly 16-50km above Earth's surface. Less dense than the tropo. Contains ozone layer. Upper layers of the stratosphere absorb UV radiation and convert it to infrared radiation, which is released as heat. This reduces the amount of UV radiation absorbed in the lower stratosphere. The higher in the stratosphere you are the warmer it is.
Thermohaline circulation
oceanic circulation pattern that drives mixing of surface water and deep water. Moves heat and nutrients around the globe. Warm currents flow from the Gulf of Mexico to the very cold North Atlantic Ocean. Some water freezes or evaporates and, as a result, the salt concentration of the water increases. This increases the density of the water causing it to sink to the ocean floor. Cold water travels along the ocean floor connecting the world's oceans. Eventually, the cold deep water rises to the surface and circulates back to the North Atlantic.
Ozone layer
pale blue gas composed of molecules made up of 3 oxygen atoms (O3). It absorbs most of the Sun's ultraviolet-B (UV-B) radiation and all of its ultraviolet-C (UV-C) radiation. The ozone layer provides critical protection to our planet. UV radiation can hit Earth due to holes in the ozone layer as a result of a split in O3 molecule. Otherwise UV radiation is reflected and absorbed.
Upwelling
surface currents diverge due to heat and wind causing the water to evaporate or spill over, deeper waters rise and replace the water that's moved away. Deep water bring with it nutrients from the ocean bottom that supports a large pop of producers -> large fish pop -> support commercial fisheries.
Albedo
the percentage of incoming sunlight reflected from Earth's surface. The higher the albedo, the more solar energy it reflects, and the cooler the surface. Ex, white, snow covered polar regions have an albedo of 80-90% The lower the albedo the more solar E that is absorbed and so the warmer the surface is. Ex. dark, tropical regions/ water have an albedo of 10-20%
