Global Climates and Biomes (Terrestrial) Chapter 4 Global Climates and Biomes (Terrestrial)

Weather and Climate Weather short-term atmospheric conditions in a specific region: temperature, precipitation, humidity, clouds and wind speed Climate the average weather in an area over long periods of time (decades)

Unequal heating of Earth Atmospheric convection currents Processes that affect the distribution of temperature and precipitation: Unequal heating of Earth Atmospheric convection currents Rotation of Earth Tilt of Earth

Earth’s Atmosphere Earth Troposphere Stratosphere Mesosphere Thermosphere Exosphere

Troposphere We live here!!! 16 Km (10 miles) above the Earth’s Surface Closest to earth This is where weather occurs and airplanes fly Most dense layer (molecules closer together) Has the most Nitrogen, Oxygen, and Water Vapor Temperature decreases with altitude Tropospheric Ozone is here BAD OZONE or SMOG

Stratosphere: 16km to 50km (10 to 31 miles) above Earth’s Surface Less dense (particles spread further apart) than troposphere Temperature increases with altitude Ozone layer- ozone forms a layer of pale blue gas Weather balloons travel here

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Stratospheric Ozone = Good Ozone Ozone = O3 Absorbs most UV-B and all UV-C radiation Ozone layer serves as a protective layer Hole in the ozone is getting smaller due to legislation like the 1986 Montreal Protocol (we will talk about later in detail)

The good and the bad…

Mesosphere- 50km to 100km above Earth’s Surface (meso = middle) Directly above the stratosphere Temperature decreases with altitude Can decrease to -143 C or -225 F Coldest layer of the atmosphere Meteors burn up here Large windstorms occur here (wind speeds up to 320 km/hr)

Thermosphere- 90km to 500/1000km 56 miles- 311/621 miles Above the mesosphere and below exosphere Blocks x-rays and UV-radation Absorbs high energy solar radiation (This causes this layer to have high temp) Really high temperatures 2000 degrees C/ 3630 degrees F Charged gas molecules glow when hit by solar energy this and magnetic forces at the poles = Northern Lights/ Aurora Borealis and Aurora South/ Australis

Thermosphere https://www.youtube.com/watch?v=eJV_wlCm6ms

Exosphere- 600km and beyond Outermost layer of the atmosphere Least dense (air is extremely thin atoms rarely collide) Satellites orbit here Contains hydrogen, helium, oxygen, and carbon dioxide

Elements in the Atmosphere Nitrogen Water Vapor Oxygen Krypton Argon Hydrogen Carbon Dioxide Xenon Helium Ozone Methane

Unequal heating of Earth Atmospheric convection currents Processes that affect the distribution of temperature and precipitation: Unequal heating of Earth Atmospheric convection currents Rotation of Earth Tilt of Earth

Unequal Heating of Earth Varying angles Varying surface area Light Reflection

Varying Angles

Varying Surface Areas

Unequal heating- Albedo Some areas on earth reflect more light Albedo- percent of incoming light reflected from a surface HIGH Albedo= more solar energy reflected/ less energy absorbed White surfaces (snow) have a higher albedo than black surfaces (asphalt) Average albedo on earth is 30%

Atmospheric Convection Currents Properties of Air that determine Air Circulation (movement): Density Water vapor capacity Adiabatic heating/cooling Latent heat release

Properties of Air: Density Less dense air rises (warm air) More dense air sinks (cold air)

Properties of Air- Water Vapor Capacity Warm Air= More Water Vapor Hot summer days = High Humidity Saturation Point maxiumum amount of water vapor that can be in the air at a given temperature

Water Vapor and Saturation Point When temperature decreases saturation point decreases water vapor condenses into water clouds form precipitation occurs

Properties of Air: Pressure Changes and Adiabatic heating/cooling Adiabatic Cooling= As air rises, the pressure decreases Lower pressure = expanded volume and decreased temperature Adiabatic Heating = As air sinks, the pressure increases Higher pressure = decreased volume and increased temperature

Properties of Air: Water Vapor Latent Heat release Latent Heat Release- is when water vapor in the atmosphere condenses into liquid water this releases energy (in the form of heat) Whenever water vapor in the atmosphere condenses, the air will become warmer and rise.

Properties of Air: Water Vapor Latent Heat release Latent Heat Release- is when water vapor in the atmosphere condenses into liquid water this releases energy (in the frm of heat) Whenever water vapor in the atmosphere condenses, the air will become warmer and rise.

Properties of Air

Atmospheric Convection Currents Global patterns of moving air caused by unequal heating

Convection Cells Hadley Cells Ferrel Cells Polar Cells

Hadley Cells Convection Cells that cycle between the equator and 30 degrees (north and south)

Intertropical Convergence Zone (ITCZ) The ITCZ occurs where the most sun is received Near the equator, but location varies because of tilt of the earth (between 23.5 degrees north and south) Dense clouds Thunderstorms

Polar Cells Polar Cells are convection cells that cycle between 60 and 90 degrees (North/South) Air rises at 60 degrees (N/S) and sinks at the poles (90 degrees N/S)

Ferrel Cells Ferrel Cells are convection cells between 30 and 60 degrees (north and south) Move air opposite of Hadley Cells They cause winds to be variable

Earth’s Rotation The surface moves faster at the equator than at the poles 1 rotation = 24 hours (mind blown…) The circumference at the equator is 40,000 km The circumference at the poles is 0 km

Coriolis Effect Faster rotation at the equator, causes a deflection of objects that are moving directly north or south Coriolis Effect= deflection of an object’s path due to earth’s rotation In the Northern Hemisphere the path of an object’s deflection = clockwise In the Southern Hemisphere the path of an object’s deflection = counter clockwise

Coriolis Effect https://www.youtube.com/watch?v=i2mec3vgeaI

Prevailing Winds Prevailing Winds are wind patterns produced by atmospheric convection currents and coriolis effect. 3 types of Prevailing Winds: Trade winds Westerilies Easterlies

Trade Winds Northeast Trade Winds are produced by the North Hadley Cells Winds are deflected to the west (clockwise) Southeast Trade Winds are produced by the South Hadley Cells Winds are deflected to the west (counter clockwise)

Westerlies Westerlies are prevailing winds produced from the Ferrel cells The winds are variable because of a mixture of air currents from the Hadley and Polar cells Near 30 degrees, the winds move away from the equator Winds deflect to the east Winds come from the northwest or southwest

Easterlies Easterlies are winds produced from the Polar Cells Winds come from the Northeast (clockwise) or Southeast (counter clockwise)and are deflected west Moving air away from the poles

Earth’s Tilt Earth’s axis is tilted 23.5 degrees When the northern hemisphere is tilted toward the sun (that is summer for the north) When the northern hemisphere is tilted away from the sun (that is winter for the north)

Seasons: In northern hemisphere, southern hemisphere is opposite… Spring March Equinox (20th/21st): the sun strikes the equator directly, 12 hours of day and 12 hours of night Summer June Solstice (20th/21st): Sun directly above the tropic of cancer (23.5 degrees North lat) Longest day of the year for north hemi

Seasons: In northern hemisphere, southern hemisphere is opposite… Fall September Equinox (22nd/23rd): the sun strikes the equator directly, 12 hours of day and 12 hours of night Winter JuDecember ne Solstice (21st/22nd): Sun directly above the tropic of capricorn (23.5 degrees south lat) Shortest day of the year for north hemi