1. Atmosphere & Climate Change
Section #1:
Climate & Climate Change

2. Climate
the long-term prevailing weather conditions at a particular place based upon records taken
determined by a variety of factors including latitude, atmospheric circulation patterns, oceanic circulation patterns, the local geography, solar activity, & volcanic activity

3. Most Important Factor = Latitude
the distance from the equator measured in degrees north or south of the equator
0° = the equator
90° north = North Pole
90° south = South Pole

4. Low Latitudes
those areas closer to the equator receive a greater amount of solar energy throughout the year & the sun’s rays are more direct here which concentrates the sun’s energy
night & day are about 12 hours long throughout the year
yearly temps remain consistently high

5. High Latitudes
those areas closer to the poles receive less solar energy because the sun is lower in the sky causing the sun’s rays to be spread out over a larger surface area
hours of daylight can vary throughout the year
yearly temps vary greatly

6. Vertical vs. Oblique Solar Rays

7. Atmospheric Circulation Basics
cold air sinks because it is denser
air close to Earth’s surface will warm, expand, & rise
warm air can hold more moisture (water vapor) that cold air can
as warm air rises, it cools and condenses into liquid water to form precipitation

8. Wind
the movement of air that is created when warm, rising air is replaced at the surface with cooler air
also affected by Earth’s rotation & the amount of solar energy that warms the surface at each latitude
global wind patterns are created & show how atmospheric circulation can affect precipitation patterns

9. Global Winds

10. Deserts
air that is warmed at the equator rises & flows northward & southward to 30° north & south latitude where it sinks
the sinking air compresses causing the temp to rise
this warmer air can hold a larger quantity of water vapor
evaporation from the surface below this warm, sinking air is so great that there is little precipitation returning water to Earth, thus creating very dry conditions at the surface

11. Prevailing Winds
winds that blow predominantly in one direction throughout the year
Earth’s rotation cause these winds to be deflected to the right in the Northern Hemisphere & to the left in the Southern Hemisphere

12. Bands of Prevailing Winds
Trade Winds = between 0° & 30° north & south latitude
Westerlies = between 30° & 60° north & south latitude
Polar Easterlies = between 60° & 90° north & south latitude
Note: winds are named based on where they come from

13. Smoke from Fires Showing the Wind Direction

14. Oceanic Circulation Patterns
ocean water holds large amounts of heat which can dramatically impact climate patterns
most surface ocean currents are caused by winds & Earth’s rotation
these currents redistribute warm & cold masses of water around the planet

15. El Niño
short-term (6 to 18 months) periodic change in the location of warm & cold water masses in the Pacific Ocean
normally weak winds in the west will strengthen & push warm water eastward
produces increased rainfall in the southern ½ of the U.S., Central America, & upper parts of South America
causes drought in Indonesia & Australia

16. La Niña the opposite phase to the El Niño cycle
water in the eastern Pacific Ocean is cooler than usual, resulting in less rainfall
these two cycles combine to form the Southern Oscillation

17. Southern Oscillation

18. Pacific Decadal Oscillation
a long-term change (20 to 30 years) in the location of warm & cold water masses in the Pacific Ocean
influences the climate in the northern Pacific Ocean & North America
affects ocean surface temps, air temps, & precipitation patterns

19. Topography
temperatures will drop with elevation at a rate of about 6°C (about 11°F) for every 1000 meter increase in elevation
mountains & mountain ranges also influence the distribution of precipitation, like creating rain shadows where the mountains block moisture from reaching the opposite side of the mountains

20. Rain Shadow

21. A Solar Maximum
the sun emits an increased amount of ultraviolet radiation
this produces more ozone
this warms the stratosphere, the lower atmosphere, & the surface of the Earth

22. Sun’s 11 Year Cycle from Max to Min

23. Volcanic Eruptions
during a larger volcanic eruption, large amounts of sulfur dioxide gas can reach the upper atmosphere where it remains for up to 3 years
here it reacts with smaller amounts of water vapor & dust in the stratosphere forming a layer of haze that reflects enough sunlight to cause global temps to decrease

24. Seasonal Changes in Climate
temperatures & precipitation change with the seasons because of the tilt of Earth’s axis
the angle at which the sun’s rays strike the Earth changes as the Earth moves around the sun

25. Summers
during our summer, the Northern Hemisphere tilts towards the sun & receives direct sunlight
the number of daylight hours is greatest in the summer
thus the amount of time available for the sun to heat the Earth is greater
everything is reversed in the Southern Hemisphere

26. The Earth’s Tilt