Transcript Weather and Climate Power Point

World Geography
Weather and Climate
Factors that affect climate
• I. The Sun and Latitude:
– Tilt of the earth as the planet revolves around
the Sun.
• Determines which hemisphere receives the most
direct sunlight, which causes changing seasons.
• Sun’s energy:
– ½ of the energy is absorbed in the atmosphere
– Earth’s surface absorbs the other ½
– Solar (from the Sun) energy is converted into heat and
measured according to temperature.
The Sun and Latitude cont.
• Greenhouse Effect: earth’s atmosphere
traps heat energy.
• The greenhouse effect helps keep the
planet warm, but recent evidence shows
that the Earth has gotten noticeably
warmer. What might cause this?
The Sun and Latitude cont.
II. “Atmospheric Pressure”
• The air around you is constantly pushing
you, a force called atmospheric pressure,
or air pressure.
• As you climb a mountain, there is less air
pushing you down, thus the air gets
thinner is harder to breath as humans.
Air pressure cont.
• At such high altitudes, air is too thin to
breath, that is why plane’s are air sealed
and pressurized.
• When you fly on a plane, your ears pop
because of the changes in air and cabin
pressure.
Air pressure cont.
- Low pressure area: when air is heated it
expands, becomes less dense, and rises,
creating a low- pressure area. As the air
rises and cools, the water vapor it carries
forms into clouds.
- Low pressure usually accompanies
unstable weather conditions.
- Centers of low pressure are called
cyclones.
• Cold air is dense and sinks towards
Earth’s surface, creating centers of high
pressure.
• High pressure systems usually bring more
stable weather conditions.
Global Wind Belts
Global wind belts cont.
• Prevailing winds: winds that blow from the
same direction most of the time.
• Sailors use the prevailing winds to guide
trips.
• The zone of winds along the equator is
calm, with no prevailing winds called the
doldrums.
Global wind belts cont.
• A front occurs when two air masses of
vastly different temperatures collide.
III. Oceans and Currents
• Oceans also affect climate.
• Location in respect to an ocean changes
climate. Landlocked areas will be cooler
than locations near oceans because of
warm currents that carry heated waters.
“Weather Factors”
• I. Precipitation:
– The process with which water changes from
liquid to a gas is called evaporation.
– The amount of water vapor in the air is called
humidity.
– Condensation is the process with which water
vapor changes from gas to a liquid.
Storms
• Hurricanes: the most powerful and
destructive tropical cyclones.
• Typhoons: hurricanes in the Western
Pacific Ocean areas (Asia).
• Tornadoes: twisting spirals of air in the
middle- latitude areas.
• The U.S. has more tornadoes than any other
country.
Climate and Vegetation Patterns
• “Tropical Climates”
– Tropical Humid Climates
• Example: Vietnam, Indonesia
• Areas close to the equator
• They never have truly cold weather.
– Because the warm air is always rising, this unstable air
leads to almost daily thunderstorms and heavy rainfall.
– In some parts of the tropical humid climates all rainfall is
concentrated into a wet season.
• Tropical wet and dry climates:
– Just to the N and S of the tropical humid
climate.
– Also called the tropical savanna climate.
• A savanna is an alternating pattern of wet and dry
season.
• “Dry Climates”
– Arid climates – stable sinking dry air all year.
– Locations include: Mexico, Southern Africa,
and South America for example.
– Soils tend to be thin and rocky.
• Semiarid climate:
– Receive more moisture than Arid climates but
less than more humid areas.
– Humid subtropical climate:
• Found on the eastern side of continents where
there are warm air ocean currents.
• Usually contains forests.
• Deciduous forests – trees that lose their
leaves during part of the year
• Coniferous forests – remain green all year.
• High latitude climates– Subarctic climate – Canada, Greenland,
Northern Russia, parts of northern Europe.
– Cold climate, but also supports vast
evergreen forests.
– Tundra climate – permanently frozen soil
called permafrost.
• Ice Cap climate – found on Earth’s polar
regions.