Download What Causes Climate? - Madison Central High

What Causes
Climate?
Notes
Introduction
• A climate is the average, year-afteryear weather conditions in an area. Two
factors are important in describing a
climate - temperature and precipitation.
• A climate region is a large area that has
similar climate throughout. For
example, all of the southwestern United
States has a hot, dry climate.
• The weather of one single day, or even
one single year IS NOT an indication of
climate.
Factors Affecting
Temperature
• Earth is divided into three temperature
zones based on latitude:
1. The tropical zone is the area near
the equator from 0° to 23.5°N and S.
2. The temperate zones are from
23.5°N and S to 66.5°N and S.
3. The polar zones are from 66.5°N and
S to the poles (or 90°N and S).
Factors Affecting Temperature
• In the Tropical Zone, there is very little
seasonal temperature change. It is
almost always warm here because
sunlight is direct all year long.
• In the Polar Zones, light is the least
direct throughout the year, so it is
always cold.
• In the Temperate Zones, sunlight is
direct only in the summer, and during
the winter, it strikes at a much more
acute angle. This leads to temperature
changes between seasons.
Factors Affecting
Temperature
• Altitude affects temperature as well.
Highland areas everywhere have cool
climates.
• For example, Mt. Kilimanjaro, which
resides in East Africa, has a peak at
6km. Temperatures drop at around
10°C for every kilometer of altitude,
meaning that at the top, it’s nearly 60°
cooler that at sea level.
Factors Affecting
Temperature
• Continental climates have hotter and
colder seasons than do marine climates.
Winters are colder, while summers are
hotter. The central part of the Unites States
has a continental climate.
Factors Affecting
Temperature
• Oceans and large lakes affect climate. A marine
climate is the climate of an area near an ocean or
large lake. Sun an area has mostly mild winter and
cool summer.
• This is because water heats up more slowly than
land. It also cools off more slowly than land. This
means that coastal areas are somewhat protected
from extreme temperature shifts.
• Remember, this is due to the relatively high
specific heat of water.
Factors Affecting
Temperature
• Marine climates are also influenced by
ocean currents.
• Warm water from the tropics can warm
up places that have very high latitudes.
For example, the Gulf Stream is a
tropical current that brings warm moist
air to Ireland and southern England,
both of which are above 50°N latitude.
Factors Affecting
Temperature
• At the same time, cooler, polar
waters can come down and bring
cold, wet air to warm, dry regions.
The California Current brings cold
water/air down from Alaska,
making the west coast of the
United States cooler than
expected for those latitudes.
Factors Affecting
Precipitation
• Prevailing winds move air masses from one
place to another. If the air started over an ocean,
it’ll be moist. If the air mass started over land, it’ll
be very dry.
• The amount of water vapor in an air mass
influences the amount of precipitation.
• The United States exists in a prevailing wind
known as the westerlies. This generally moves
air from the SW to the NE.
Factors Affecting
• SeasonalPrecipitation
winds are wind patterns that
change with the seasons over a wide
area. Monsoons are seasonal winds.
Monsoons are large sea and land
breezes that change directions with the
seasons.
• Winds flow from [H]igh pressure to
[L]ow pressure.
• In general:
• Cool air = [H]igh
• Warm air = [L]ow
Sea Breeze
L
Massive Rains
Land Breeze
H
Very Little Rains
The Seasons
• Of course, the weather changes as the seasons
change. This is most extreme in the Temperate
Zones from 23.5N to 66.5N and form 23.5S to
66.5S.
• This directly corresponds to the tilt of Earth’s axis
(23.5°) in relation to the sun.
• It’s summer when the tilt is towards the sun (July
in the Northern Hemisphere/December in the
Southern Hemisphere).
• It’s winter when the tilt is away from the sun.