Download Atmospheric Circulation

• Air near Earth’s surface generally flows from
the poles toward the equator.
• Air moves from high-pressure regions to low-pressure
regions
• high pressure regions form where cold air sinks
toward Earth’s surface
• poles
• Low-pressure regions form where warm air rises
away from Earth’s surface
• equator
• The circulation of the
atmosphere and the oceans
is affected by the rotation
of Earth on its axis
•The air flows faster and over
a farther distance at the
equator
•When air moves to the poles,
it travels faster than the land
beneath it rotates
• Causes air to flow in a curved
path
• Coriolis Effect
• The tendency of a moving
object to follow a curved
path rather than a straight
path because of the rotation
of the Earth
• Examples: wind and water
• Objects deflect to the right
in the Northern Hemisphere
and to the left in the
Southern Hemisphere
• The faster an object travels,
the greater the deflection
• The air that flows from the
poles toward the equator
does not flow in a single
strait line
•Each hemisphere contains
three looping patterns of
flow called convection cells
• Each cell correlates to an area
on Earth’s surface known as a
wind belt
• Types of wind belts
• Trade Winds
• Names according to the direction from which they flow
• Both trade wind belts meet along the equator in an area known as the
doldrums
• Air moves towards the equator from east to west (easterly)
• Westerlies
• air moves away from the equator from west to east (westerly)
• Polar Easterlies
• Strongest in Antarctica
• Often stormy where it meets with the Westerlies
• Air moves towards the equator from the pole in an easterly direction
• Jet Streams
• Narrow bands of highspeed winds that blow in
the upper troposphere and
lower stratosphere
• Types
• polar jet stream
• Subtropical jet stream
• Impacts weather patterns in
North America
• If the stream undulates further north
it results in high temperatures
• Ex: In June 2013, McGrath Alaska
had a record high of 94 degrees. A
few weeks earlier they had a record
low of 15 degrees
• If the stream undulate further south,
it results in much lower temps and
usually brings storms
• Ex: the snow the northeast has gotten
in February is because of the cold air
from Canada interacting with the
moisture of the Atlantic
• Local Winds
• Winds can also exist on a
smaller, more local scale
• Not a part of the wind belts
• Land vs Sea Breezes
• As the land heats up during the day,
its temperature rises above that of
the ocean
• Results in hotter air over land
• As the hot air rises, the cool ocean air
moves inland creating a seabreeze
• As the land cools off at night, the
air descends creating a sea bound
breeze known as a land breeze
• There are two basic wind
measurements direction &
speed
• Direction is determined by where
the wind is coming from
• Ex: a north wind is blowing from
north to south
• Instruments
• Direction is most commonly
determined using a wind vane
• Speed is determined by an
anemometer
• If a wind blows more
often from one direction,
it is known as a
prevailing wind
• In the U.S., the westerlies
consistently move
weather from west to
east across the continent