1. Chapter 18
Climate

2. Southwest US – hot, dry all year.
CLIMATE
General conditions of temp & precipitation for an area over a long period of time.
Southwest US – hot, dry all year.

3. Climate of a region is determined by:
1. Temperature
2. Precipitation

4. FACTORS THAT AFFECT TEMP
Latitude- measure of the distance N & S of equator.
Closer to equator, more direct sunlight, warmer climate.
Farther away from equator, less sunlight, cooler climate.

5. 2. Elevation- as elevation increases, air cools & can’t hold as much moisture so temp decreases.

6. OCEAN CURRENTS

7. 3. Ocean Currents- a river of water that flows in a definite path in the ocean.
The surface temp of water affects the temp of the air.

8. Warm water currents travel away from equator.
Cold water currents travel toward the equator.
Land near currents is affected by the temp of the ocean currents.

9. 4. Distances From Water
Oceans greatly moderate the temps of nearby land.
Water heats/cools slower than land.

10. FACTORS THAT AFFECT PRECIPITATION
Prevailing Winds- Carries different amounts of moisture which affects precipitation.

11. Winds that blow from sea to land carry more moisture.
Places in the center of a land mass have dry climates.

12. Region that receives less than 25cm of precipitation in one year.
DESERT
Region that receives less than 25cm of precipitation in one year.

13. 2. MOUNTAIN RANGES Act as barriers to winds
Mountains cause air to rise
2 parts of a mountain: windward side & leeward side

14. A) Windward side- receives a lot of precipitation. Faces the wind
A) Windward side- receives a lot of precipitation. Faces the wind. B) Leeward side- drier air. Faces away from wind.

15. How Mtns. Affect Precip.
Air is forced up. As it rises, it starts to cool.
Cold air can’t hold as much moisture so precipitation occurs on the windward side.
Air that comes over the Mtn. (leeward side) is drier.

16. 3. SEASONAL WINDS
Monsoon- a major landbreeze or seabreeze that changes direction with the seasons.

17. THE SEASONS
Most places outside the tropics have 4 seasons: summer, fall, winter, & spring.

18. Causes of Seasons
Tilted Axis- the tilt of the earth’s axis as the earth travels around the sun.
Tilted on an angle of 23.5

19. The north end of the axis is pointed away from the sun for part of the year (Winter)& toward the sun for another part of the year (Summer).

21. In summer, N. hemisphere is tilted towards the sun = more direct sunlight, warmer temps. (June)
In the winter, N. Hemisphere is pointed away from sun = less sunlight, colder temps. (December)

23. Sec. 2 Climate Regions

24. CLASSIFICATION Climates are classified according to: 1. Temperature
2. Precipitation

25. 6 Main Climate Regions Tropical rainy Dry Temperate marine
Temperate continental
Polar
Highlands

26. 1. Tropical Rainy Climates
Found in low-lying lands near equator.
2 types: Tropical Wet, & Tropical Wet-&-Dry.

27. Hot/Humid, many rainy days, over 10meters/year.
Tropical Wet
Hot/Humid, many rainy days, over 10meters/year.
Windward side of Hawaii
Rain Forest- forests in which large amounts of rain fall year-round.

28. Hot, receives slightly less rain & has a distinct dry & rainy season.
Tropical Wet & Dry
Hot, receives slightly less rain & has a distinct dry & rainy season.
Savannas- tropical grassland
Southern Florida

29. Arid Climate & Semiarid Climate.
2. Dry Climates
A climate is dry if the amount of precipitation that falls is less than the amount that evaporates.
Arid Climate & Semiarid Climate.

30. Desert, with little precipitation (less than 25cm/year).
Arid Climate
Desert, with little precipitation (less than 25cm/year).
Hot, sandy & cold or rocky
Parts of California & Southwest.

31. Dry but receives 25-50cm of precipitation/year.
Semiarid Climate
Dry but receives 25-50cm of precipitation/year.
Steppe- dry region that gets enough rainfall for short grasses & bushes to grow.
Great Plains

32. 3. Temperate Marine Climate
Along the coasts of temperate continents
Humid (50F+) in summer & mild winters (20F to 64F).
Mediterranean, Humid Subtropical, Marine West Coast.

33. Coastal climate that is drier & warmer than West Coast Marine.
Mediterranean
Coastal climate that is drier & warmer than West Coast Marine.
Mild winters, cool summers, & moderate rainfall. (agriculture)
Southern California,

34. Warm, dry summers & rainy winters
Marine West Coast
Warm, dry summers & rainy winters
Northern California to Southern Alaska
Because of heavy precipitation, thick forests grow here.

35. Hot/Humid summers & cool winters. Warm & wet. Southeast US
Humid Subtropical
Hot/Humid summers & cool winters. Warm & wet.
Southeast US
Forests, oranges, peaches, sugarcane.

36. 4. Temperate Continental Climate
Only found on continents in the Northern Hemisphere.
Not influenced by oceans- you get extreme temps.
50F or above to 20F or below

37. NE United States, Mid West US.
Humid Continental
Hot, humid summers & cold winters with moderate precipitation year round.
NE United States, Mid West US.

38. Short, cool summers & long, cold winters with light precipitation.
Subarctic
Short, cool summers & long, cold winters with light precipitation.
Eastern Alaska, Canada

39. Coldest climate, Avg. temps below 50F in warmest month.
5. Polar Climate
Coldest climate, Avg. temps below 50F in warmest month.
Includes North & South Poles, Icecaps, & tundras.

40. Stretches from northern Alaska, Canada, & Russia.
Tundra
Stretches from northern Alaska, Canada, & Russia.
Short cool summers, bitterly cold winters.

41. PERMAFROST
Permanently frozen land, water cannot drain away so the soil is wet & boggy in summer.
No trees, but moss/grass/shrubs grow.

42. Cooler & wetter than nearby lowlands. Temp decreases with altitude.
6. Highlands Climate
Cooler & wetter than nearby lowlands.
Temp decreases with altitude.
Short summers, long, severe winters. NW US.

43. Sec. 3
Long-Term Changes

44. Studying Climate Changes
If plants or animals today need certain conditions to live, then similar plants & animals in the past also required those conditions.

45. Types of Evidence to Study Climate Changes
Fossil evidence
Tree rings
Pollen

46. Tree Rings
Scientists study the pattern of thick or thin tree rings to tell about warm/cool or wet/dry climate.

47. Cold periods, Glacial episodes.
Ice Ages
Cold periods, Glacial episodes.
Huge sheets of ice (glaciers) cover large parts of the Earth’s surface.

48. Last Ice Age was 10,500 yrs ago. Sheets of ice covered N Europe, & North America as low as Indiana & Iowa.
A lot of water was frozen causing ocean level to drop.

49. Movement of Continents
CAUSES OF CHANGE
Earth’s position
Solar energy input
Volcanic Activity
Movement of Continents

50. Section 4

51. Short-Term Climate Changes
1. Ocean Currents- El Nino, La Nina
2. Global Warming
3. Ozone Depletion

52. Brings severe conditions- rain or drought.
El Nino
Unusual pattern of warm winds & water that form over the Pacific Ocean & move eastward towards the coast of South America.
Brings severe conditions- rain or drought.

53. Surface waters of eastern Pacific Ocean are colder than usual.
La Nina
Surface waters of eastern Pacific Ocean are colder than usual.
Brings colder winters & greater precipitation to Pacific NW & North Central US.
Greater hurricane activity in western Atlantic Ocean.

54. A gradual increase in temp. of earth’s atmosphere. Greenhouse effect
GLOBAL WARMING
A gradual increase in temp. of earth’s atmosphere.
Greenhouse effect
Greenhouse gases: carbon dioxide, methane trap heat.
Human activities add greenhouse gases to the environment.

55. Chlorofluorocarbons (CFC’s) are a major cause for depletion.
Ozone Depletion
Chlorofluorocarbons (CFC’s) are a major cause for depletion.

56. CFC’s in air conditioners/aerosol sprays release CFCs into the air & they stay in the atmosphere & breakdown the ozone layer.