Transcript Chp. 18 Climate

• General conditions of temp
& precipitation for an area
over a long period of time.
• Southwest US – hot, dry all
year.
•Climate of a region is
determined by:
1. Temperature
2. Precipitation
FACTORS THAT AFFECT
TEMP
1. 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.
2. Elevation- as elevation
increases, air cools & can’t
hold as much moisture so
temp decreases.
OCEAN CURRENTS
•
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.
• 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.
4. Distances From Water
• Oceans greatly moderate the
temps of nearby land.
• Water heats/cools slower than
land.
FACTORS THAT AFFECT
PRECIPITATION
1.Prevailing Winds- Carries
different amounts of moisture
which affects precipitation.
• Winds that blow from sea to
land carry more moisture.
• Places in the center of a land
mass have dry climates.
• Region that receives less
than 25cm of precipitation
in one year.
2. MOUNTAIN RANGES
• Act as barriers to winds
• Mountains cause air to rise
• 2 parts of a mountain:
windward side & leeward side
A) Windward side- receives a
lot of precipitation. Faces the
wind. B) Leeward side- drier
air. Faces away from wind.
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.
3. SEASONAL WINDS
•Monsoon- a major
landbreeze or seabreeze that
changes direction with the
seasons.
THE SEASONS
•Most places outside the
tropics have 4 seasons:
summer, fall, winter, &
spring.
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
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).
• 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)
CLASSIFICATION
•Climates are classified
according to:
1. Temperature
2. Precipitation
6 Main Climate Regions
1. Tropical rainy
2. Dry
3. Temperate marine
4. Temperate continental
5. Polar
6. Highlands
• Found in low-lying lands near
equator.
• 2 types: Tropical Wet, &
Tropical Wet-&-Dry.
• Hot/Humid, many rainy days,
over 10meters/year.
• Windward side of Hawaii
• Rain Forest- forests in which
large amounts of rain fall yearround.
• Hot, receives slightly less
rain & has a distinct dry &
rainy season.
• Savannas- tropical grassland
• Southern Florida
• A climate is dry if the amount
of precipitation that falls is
less than the amount that
evaporates.
• Arid Climate & Semiarid
Climate.
• Desert, with little
precipitation (less than
25cm/year).
• Hot, sandy & cold or rocky
• Parts of California &
Southwest.
• Dry but receives 25-50cm of
precipitation/year.
• Steppe- dry region that gets
enough rainfall for short
grasses & bushes to grow.
• Great Plains
• Along the coasts of temperate
continents
• Humid (50F+) in summer &
mild winters (20F to 64F).
• Mediterranean, Humid
Subtropical, Marine West
Coast.
• Coastal climate that is drier &
warmer than West Coast
Marine.
• Mild winters, cool summers, &
moderate rainfall. (agriculture)
• Southern California,
• Warm, dry summers & rainy
winters
• Northern California to Southern
Alaska
• Because of heavy precipitation,
thick forests grow here.
• Hot/Humid summers & cool
winters. Warm & wet.
• Southeast US
• Forests, oranges, peaches,
sugarcane.
• Only found on continents in
the Northern Hemisphere.
• Not influenced by oceans- you
get extreme temps.
• 50F or above to 20F or below
• Hot, humid summers &
cold winters with moderate
precipitation year round.
• NE United States, Mid
West US.
• Short, cool summers & long,
cold winters with light
precipitation.
• Eastern Alaska, Canada
• Coldest climate, Avg. temps
below 50F in warmest month.
• Includes North & South Poles,
Icecaps, & tundras.
•Stretches from northern
Alaska, Canada, & Russia.
•Short cool summers,
bitterly cold winters.
PERMAFROST
• Permanently frozen land, water
cannot drain away so the soil is
wet & boggy in summer.
• No trees, but
moss/grass/shrubs grow.
•Cooler & wetter than
nearby lowlands.
•Temp decreases with
altitude.
•Short summers, long,
severe winters. NW US.
Studying Climate Changes
• If plants or animals today
need certain conditions to
live, then similar plants &
animals in the past also
required those conditions.
Types of Evidence to Study
Climate Changes
• Fossil evidence
• Tree rings
• Pollen
• Scientists study the pattern
of thick or thin tree rings to
tell about warm/cool or
wet/dry climate.
• Cold periods, Glacial episodes.
• Huge sheets of ice (glaciers)
cover large parts of the Earth’s
surface.
• 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.
1.Earth’s position
2.Solar energy input
3.Volcanic Activity
4.Movement of Continents
1. Ocean Currents- El Nino,
La Nina
2. Global Warming
3. Ozone Depletion
• 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.
• 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.
• 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.
•Chlorofluorocarbons
(CFC’s) are a major cause
for depletion.
•CFC’s in air
conditioners/aerosol sprays
release CFCs into the air &
they stay in the atmosphere
& breakdown the ozone
layer.