Transcript Climate and Elevation

What is Climate?
Climate is the general weather pattern of an area
over many years or long-term weather conditions.
Factors Effecting Climate
Although climate is most affected by latitude, it is
also affected by geography (landforms), humidity,
and altitude (elevation).
Climate & Latitude
As latitude changes, so does climate.
This is because the Sun heats the Earth
unequally, due to Earth’s spherical shape.
 The Low Latitude zone, or Tropical zone, is located between the Tropics of Cancer
and Capricorn.
 The sun hits the earth most directly here, creating the hottest region of the world.
 Most regions of the Tropical zone have a dry season and a wet season. The wet
season occurs during the summer, when most of the annual precipitation falls. The
dry season is in the winter.
 The Mid-Latitudes, or the Temperate zones are found between the Tropics and the
Circles.
 Temperatures here are generally more mild than in the Tropics. Warm air masses
come from the Tropics during summer, and Cold air masses come from the Polar
regions during the winter.
 As a result, these areas have more diverse weather, vegetation, and bigger
differences between seasons.
 The High Latitudes, or the Polar regions, are located between the circles and the
poles.
 The two polar regions take turns getting continuous sunlight for 6 months. The
North Polar Region receives daylight from March 20 to September 23, and the
South Polar Region receives daylight for the rest of the year. A day in the polar
regions literally lasts one year.
 Obviously, cold temperatures and little vegetation is the norm here.
Latitude plays a huge role, if not the most important
role in determining climate.
For example, compare Antarctica and Saudi Arabia.
As a result of latitude’s large control over temperature,
latitude also determines:
 Precipitation
 Wind Patterns
 Ocean Currents
Landforms and Climate
• Climates even at the same latitude can be very different, as
landforms such as bodies of water and mountains have a huge
impact on climate.
• For example, large bodies of water heat or cool slowly, making
water temperatures more stable than land temperatures. This
makes the coastal lands have more stable weather than that of
inland areas.
Water has stable
temperatures.
Makes coastal lands have
stable temperatures and
weather too.
• Mountains have a large impact on climate as well, by using orographic
lifting to take precipitation from the incoming air masses, denying the
neighboring land any rain. This phenomenon is known as the rain shadow
effect.
• Not only do landforms affect climate, but climate also has an effect on
landforms, such as winds eroding a mountain. Precipitation, wind,
temperature, and other statistics of climate can create or destroy landforms.
Dunes are created by wind carrying
and depositing sediment.
Rock formed by wind
and rain erosion.
• Landform breezes are common in the mountainous or hilly areas.
Resulting from the higher slopes heating and cooling faster than the
valleys.
• During the day, the high slopes heat faster than the valleys, creating
low pressure. This draws a breeze from the valleys, because air moves
from high pressure to low pressure.
• At night, the high slopes begin to cool faster, getting high pressure,
so breezes flow from the highlands to the valleys.
Day
Heat/cools faster
Heat/cools slower
Night
• What’s on the land is important too. Deserts, for example, have
little moisture, so rain rarely occurs. Or, in the Tundra, it would be
too cold for evaporation, also limiting precipitation.
• The location of landforms are another factor. Areas more inland
typically receive less rain then the coastal area, simply because the
air masses from the ocean already gave it all to the coastal areas.
Most clouds die before they
reach the inland areas.
Costal areas get a lot of
precipitation from the ocean.
Coastal
Inland
Ocean
Climate and Elevation
Climate and Elevation
· Elevation is how high above sea level you are.
· It influences climate at all latitudes.
Quito, Ecuador is nearly on
the Equator. It also lies in the
Andes Mountains at an
elevation of more than 9,000
feet (2,743 meters). Average
temperatures are about 32°F
(17°C) cooler than the
lowlands around it.
Climate and Elevation
· Elevation can cause significant differences in climate (although this varies in different
locations).
· The effects of elevation on climate follow a general pattern. For example, the climate
in the Andes Mountains will be similar to the climate in the Alps.
Andes Mountains
Alps
Elevation Affects Climate…Why?
· Elevation influences climate because of
the relationship between the elevation of
a place and its temperature.
· The higher you are, the less dense the
air is (thinner air). Less dense air does not
hold heat well. Therefore, the higher you
are, the colder it is.
In mathematical terms:
· The temperature decreases by about
3.5°F to 4°F for every 1,000 feet (305
meters) increased.
· 1 mile of elevation gained is equal to 800
miles of latitude gained.
Elevation and Life Zones
What are “life zones”?
They are groups and areas of
similar vegetation and climate.
At different
elevation levels,
there are different
types of vegetation.
The different life zones of an area depend on several factors such as soil type
and the distance that area is from the sea.
Elevation and Temperature
It is colder at higher elevations.
This is caused by low atmospheric
pressure. There is less air pushing
down, so the air molecules spread
out and lose energy. Even though
it is closer to the sun, because of
the thinner atmosphere (or air),
the climate is colder.
Elevation and
· Because there is low air
pressure and few
obstructions, high altitudes
face high winds.
· For every mile of elevation,
wind speeds are increased by
8 miles per hour.
· High winds cause less plant
growth (including large
trees). Many mountains have
“tree lines”. A tree line is a
border between lower
elevation life zones (where
trees live) and higher
elevation life zones (winds
are too rapid).
Climate and Mountains
High elevation areas have
their own life zones. They also
affect the climate of
surrounding low elevation
areas. Mountains block the
movement of moist air from
bodies of water. Their melting
snow creates available water
and climates below that
contrast with the seasons. The
inconsistent geography of
mountain peaks cause many
micro-climates.
Elevation and Precipitation
Why is precipitation more frequent at high elevations?
Air that is forced up a mountainside cools rapidly. Evaporated water in
the air then condenses, creating clouds and rain. This process is known
as orographic precipitation.
Rain Shadow Effect Important Terms
Mountainsides to Know:
· Windward Side: Facing the wind.
· Leeward Side or Downwind Side: Not
facing the wind.
Rain Shadow Effect: the Complicated Version
Winds that blow over an
ocean push upward at
mountain ranges (which
act as barriers to the
flow of air across the
surface of the Earth).
Rising air cools and
releases most of the
moisture in the form of
precipitation (large
clouds and thunderstorms
may form) on the windward
mountain side. As the
parcel of air descends on
the leeward mountain
side, it is dry. The area
of dry land on the
leeward side of the
mountain is called a rain
shadow.
Rain Shadow Effect: the Simple Version
Key Points to Know:
· Warm air can hold more moisture
than cold air can.
· Warm air is lifted on the windward
side.
· As it rises, it cools.
· Moisture is squeezed out of the air.
· Dry air descends on the leeward
side.
· Windward side is wetter.
· Leeward side is drier.
· Drier area/side is called the rain
shadow.
Rain Shadow Effect Is…
…the primary cause of dry areas
such as deserts on the leeward
mountain side.
…also known as the orographic effect or
orographic lifting. This process keeps
windward sides of mountain ranges moist and
filled with vegetation but leeward sides
dry and barren.
Rain Shadow Regions and the
Mountains that Shield Them
Cascade Mountain Range
City of Spokane (receives
little rainfall)
Seattle, Washington (receives
generous amounts of rainfall)
Gobi Desert
Himalayas
Patagonia
Andes Mountains
Atacama
Desert
Death Valley
Sierra Nevada Mountains
Pacific Coast Ranges