Heating the Earth Air Pressure Energy From the Sun.
-
Upload
juliet-glenn -
Category
Documents
-
view
223 -
download
0
Transcript of Heating the Earth Air Pressure Energy From the Sun.
Heating the EarthHeating the EarthAir PressureAir Pressure
Energy From the Sun
Where We Get Our Where We Get Our EnergyEnergy
• The Sun is a major source of energy for Earth.
• You can feel the radiant energy warming your skin
• Radiation- movement of energy through empty space
Sun’s EnergySun’s Energy
Absorption of EnergyAbsorption of Energy
• Dark surfaces absorb light, and it is usually changed into heat
• Surfaces that reflect light, such as white, remain cooler
ConductionConduction• The troposphere is heated by moving
heat through matter
• How does heat move through a metal pan?
• Conduction- heat moves from an area of higher temperature to area of lower temperature
RadiationRadiation
• Radiant energy travels from the Sun through space in waves
• Radiation passes easily through the atmosphere to the surface
• Surface radiates most back into atmosphere
ConvectionConvection• Transfer of heat within a liquid or gas
• As air heats it expands, becomes lighter
• Warm air becomes lighter than cool air, so warm air rises
• Cooler, denser air sinks
Forms of EnergyForms of Energy
• Let’s look at this animation for radiation, conduction, and convection
• http://www.wisc-online.com/Objects/ViewObject.aspx?ID=SCE304
What is Air Pressure?What is Air Pressure?
• Pressure- the amount of force per unit of area
• Weight- weight (force) is measured in Newtons
• Ex.- Holding a book (pg. 260)• Force over small area causes more
pressure than a large area
Air Pressure in Air Pressure in AtmosphereAtmosphere
• Air molecules are in constant motion and pulled toward Earth’s center by gravity
• Force of all the molecules moving causes air pressure
• Air pressure is greatest near surface
ElevationElevation
• What happens to air pressure as elevation changes?
• Air pressure decreases as distance above surface increases
• Very little weight of air pressing down
Water VaporWater Vapor
• Water evaporates from lakes, rivers, and oceans
• Water vapor molecules are lighter than other gas molecules
• So, more water vapor in air, the lower the air pressure
Measuring Air PressureMeasuring Air Pressure• Barometer- air pressure is measured
with this instrument
• Air pressure pushes down on the surface of the mercury in the containter
• Standard air pressure- 760 mm of mercury or 1 atmosphere or 1,013.20 mb
BarometersBarometers
How do Winds Form?How do Winds Form?• Wind- the horizontal movement of air
along Earth’s surface
• Earth’s atmosphere is always in motion
• Winds form as cool, heavy air moves toward warm, light air
• Cool air moves along the surface toward warmer air
How do Winds form?How do Winds form?• Winds are also caused by differences
in air pressure
• Cold, heavy air have high air pressure (Highs)
• Warm, light air have low air pressure (Lows)
• Speed of wind depends on the differences in air pressure
Air CurrentsAir Currents
• Air currents- up-and-down movements of air
• Some areas of Earth are warmed more than others
• Warmer air expands, becomes less dense
• Figure 11-21 pg. 266
Global WindsGlobal Winds
• Winds blow from regions of high pressure to regions of low pressure
• Differences in air pressure produce patters of global winds
• Large wind systems that circle the Earth
Global WindsGlobal Winds
• At the equator, warm air rises and moves toward the poles
• At the poles, cool air sinks and moves toward the equator
• Why do we receive cold winds during the winter in Nebraska?
Coriolis EffectCoriolis Effect• Winds curve as they move from high-
to low-pressure regions
• Winds toward equator curve to the west in the Northern Hemisphere
• Winds toward poles curve to the east
• Wind directions are reversed in Southern Hemisphere
Coriolis EffectCoriolis Effect
Trade WindsTrade Winds
• Prevailing pattern of easterly winds
• Found mainly in the tropics
• Responsible for steering tropical storms in the southern hemisphere
Prevailing WesterliesPrevailing Westerlies
• Blow strongest between 35-65 degrees latitude
• Felt strongest during winter seasons
• Blow from west to east
• Responsible for steering cyclones
Polar EasterliesPolar Easterlies
• Cold, dry winds that blow at high latitudes
• Blow from east to west
• Often weak and irregular winds
Sea and Land BreezesSea and Land Breezes
• All winds are caused by temperature differences and changes in air pressure
• Breeze coming from the sea toward the land is a sea breeze
• Breeze coming from the land toward the sea is a land breeze
Sea BreezeSea Breeze
• During the day, air over land is warmer and lighter than air over water
• The cooler, heavier air over the ocean moves in toward the land
• The result is a sea breeze
Sea BreezeSea Breeze
Land BreezeLand Breeze• At night, land cools faster than water
• Air over land becomes cooler than the air
• Heavier air over the land moves toward the water
• Warmer, lighter air rises over the land
Land BreezeLand Breeze