1. Unit 6 Climate and Global Climate Change

2. Climate The LONG TERM weather patterns for an area.
Describes monthly or annual variations in:
Temperature
Precipitation
Wind
Other weather variables

3. What Affects Climate?
1. Latitude:

4. Equator receives more direct sunlight → Warmer Climates
North & South of equator sunlight is indirect → Cooler Climates

5. Climate Zones: Tropical Zone: Equator to 23.5° N & S
Temperate zone: 23.5° ° N & S
Polar zone: 66.5° to N & S poles
Polar Zone
Temperate Zone
Tropical Zone
Temperate Zone
Polar Zone

6. 2. Topography
Water heats & cools more slowly than land: Earth’s Oceans moderate coasts → coastal climates

7. ↑ altitude, ↓ temp
Leeward side of mountains → drier air

8. 3. Air Masses Continental (dry) vs Maritime (wet)
Tropical (warm) vs Polar (cold)

9. 4. Circulation Cells
Cells of air circulation are driven by solar energy & earth’s rotation
These cells transport energy & heat from equator to poles

10. Climate Classification
Köppen classification system Divides climates based on average temperatures, precipitation & vegetation

12. Global Climate change
A pattern of change that occurs over many years (NOT seasonal variations from year to year)
Global warming: the increase in average global temperature that has occurred over MANY years

13. Greenhouse Gases Heat trapping gases in the atmosphere: Carbon Dioxide
Methane
Nitrous Oxide
Water vapor
Effects on the climate depend on:
How much is produced
How long it stays in the atmosphere
How much heat it can trap

14. Water Vapor Water vapor increases as the Earth’s surface warms
Water vapor leads to climate warming
Climate warming leads to more evaporation of water & more water vapor – a positive feedback loop

15. Natural Causes of Climate Change

16. Earth’s Climate in the Past

18. Earth’s Wobble: the 26,000 year precession cycle affects Earth’s seasons
Earth’s Orbit: changes from circular to elliptical over a 100,000 year cycle

19. Volcanic Activity: volcanic ash in the atmosphere blocks the Sun and cools Earth’s climate

20. Solar Activity: sunspot cycles affect temperatures on Earth

21. Sunspots and Sunspots Cycles:
Occur ~every 11 years
Dark spots up to 50,000 miles wide
Move across the surface of the sun
Give off more energy

22. Photosynthesis
Plants take in CO2 (a greenhouse gas) and put out O2. This reduces greenhouse gases

23. El Nino Southern Oscillation (ENSO)
Cycles of El Nino, warmer waters, and La Nina, cooler waters, off South America.
Causes cycles of wet & dry weather

24. Microclimates
A localized pocket with a climate different from the surrounding area.
Example:

25. Using ice cores, scientists found there is more CO2 in atmosphere today than in past

26. The level of the greenhouse gases methane, CO2, and nitrous oxide are increasing.

27. Carbon Dioxide (CO2) 55% of human produced greenhouse gas Comes from:
Fossil fuel combustion for power
Cutting down or burning trees
Industrial processes (making cement or chemicals)
Can stay thousands of years

28. Methane (CH4) 30% of human produced greenhouse gas Comes from:
Livestock (cows and sheep)
Landfills
Natural gas
Mining coal
Stays ~12 years
Traps 20 times more heat than CO2

29. Nitrous Oxide (N2O) 5% of human produced greenhouse gas Comes from:
Farming (fertilizer)
Fossil fuel combustion
Industrial processes
Stays ~114 years
Traps 298 times more heat than CO2

30. Sources of Greenhouse Gas emissions in US
Electricity production (32%)
Fuel combustion for transportation (20%)
Industrial processes (20%)
Agriculture(10%)
Residential (10%)

31. Heat Islands Cities and urban centers with many concrete buildings and asphalt have a warmer climate than surrounding rural areas