1. Air, Weather, and Climate

2. Earth’s Atmosphere
Compared to the size of the Earth (12000 km), the atmosphere is a thin shell (120 km)
Composed of:
~78% N2 gas
21% O2 gas
1% argon gas and other permanent gases

3. If the Earth is compared to this Orange…
the Earth’s atmosphere would be thinner than the layer of pesticide on this Orange’s surface

4. Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Ionosphere
Exosphere

5. Troposphere Closest to the earth’s surface Where we live
Very thin (averaging 11 km or 7 miles high)
Densest layer
Temp decreases as altitude increases

6. Stratosphere Above the troposphere
extends to 50 kilometers (31 miles) high
dry and less dense
UV rays reach higher altitudes and warm them
Ozone layer
Absorbs?

7. Mesosphere extends to 85 kilometers (53 miles) high
temperature decrease with altitude reaching °C at the top

8. Thermosphere extends to 600 kilometers (372 miles) high
temperatures go up as altitude increases due to absorption of solar radiation by oxygen
molecules so few and far between that they collide rarely
Farthest away from earth’s surface

9. Ionosphere Within the thermosphere
Contains ions when hit by solar energy begin to glow and produce light
Aurora Borealis
reflects many types of radio waves allowing them to bounce around the world

10. Exosphere
Top of the thermosphere and continues until it merges with interplanetary gases, or space (372 to 6200 miles)

11. Seasonal Changes Occurs due to earth’s axis being tilted
Creates opposite seasons
Determines global air circulation patterns

12. Seasons Short periods of climatic change.
Certain areas receive changing amounts of radiation throughout the year

13. Earth’s Seasons Earth SUMMER (Northern Hemisphere)
North Pole
Equator
Earth
South Pole
WINTER (Southern Hemisphere)

14. Earth’s Seasons Continued….
Tilt of the Earth’s axis towards or away from the sun creates the seasons
WINTER (Northern Hemisphere)
North Pole
South Pole
Equator
Earth
SUMMER (Southern Hemisphere)

15. Weather driven by atmosphere
atmospheric conditions over short time periods (hours or days) in small geographic areas
produced by interacting air masses
Types of weather
Warm Front-warm air displaces cool air
Cold Front-cooler air displaces warmer air
Severe-hurricanes, thunderstorms, tornadoes

16. Weather Contribute to Weather Air temperature Air pressure Humidity
Cloud cover
Precipitation
Winds

17. Air Temperature
As solar energy reaches the equator, regions heat up more than the poles.
Warm air and water at the equator travel toward the poles while cold air and water at the poles travel toward the equator in an attempt to equalize the temperature
Constant struggle = changing weather

19. Air Pressure Caused by the weight of air pressing down on the Earth
High pressure-cool, dense air that descends towards surface of earth
Fair weather
Low pressure-less dense warm air goes toward the center of a low pressure air mass
Produces cloudy and stormy weather
Air pressure changes with weather

21. Humidity and Cloud Cover
Relative humidity
Cloud Cover
clouds cool the planet
Albedo
reduces the amount of heat that radiates into space

22. Winds Speed is determined by differences in pressure Coriolis effect
Deflection of objects moving in a straight path relative to the earth’s surface
Proportional to the speed of the earth’s rotation at different latitudes
as latitude increases and the speed of the earth’s rotation decreases, Coriolis effect increases

23. Winds cont. Hadley cells Solar energy warms humid air in tropics
Warm air rises, cools, condenses and precipitates
Dry air sinks and is warmed
Hot dry air causes deserts

24. Climate Climate – long term weather patterns driven by atmosphere
determines distribution of biomes across Earth

25. What Factors Control Climate?
Latitude
Elevation/topography
Nearby water
Uneven heating of earth’s surface
Ocean currents
Vegetation
Prevailing winds
Seasons

26. Ocean Currents Warm/cold currents influence land climate
Currents redistribute heat from sun which influences climate
Gulf Stream current
Upwelling-occurs along the west coasts of most continents
Cold, nutrient filled water

27. ENSO (El Nino Southern Oscillation) Cycle
Warm phase of ENSO
El Nino – trade winds near SA weaken; allows warm equatorial water from the western Pacific to move eastward toward the west coast of SA
Suppresses upwelling; decreases productivity
Alters weather
Cooler, wetter conditions in the se US
Cold phase of ENSO
La Nina
Trade winds strengthen
Upwelling of nutrient rich waters
Drier conditions in the se US

28. “Natural” Greenhouse Effect
Solar radiation passes through the atmosphere.
~51% of the sun's radiation reaches the surface
This energy is then used in number of processes including:
heating of the ground surface
melting of ice and snow
evaporation of water
plant photosynthesis
~30% is reflected back to space by clouds and the surface
~19% of the energy available is absorbed by clouds and gases
absorb and reradiate this outgoing radiation, storing some of the heat in the atmosphere, thus producing a net warming of the surface

29. “Natural” Greenhouse Effect cont.
Kept the Earth's temperature about 60° F warmer than it would otherwise be.