Transcript The Atmosphere Section 3: Atmospheric Pressure and Winds

The Atmosphere
Section 3: Atmospheric
Pressure and Winds
Mrs. Mannel
Earth Science
Why Air Moves
 Wind
is moving air that is created
by differences in air pressure
 The greater the pressure is, the
faster the wind moves
 Differences in air pressure is
created by uneven heating of the
Earth (warm air rises, cooler air is
more dense and sinks)
Pressure Belts
Coriolis Effect

The movement of
wind is affected by
the rotation of the
Earth
 The Coriolis Effect is
the curving of
moving objects by
the Earth’s rotation
 NH – to the right
 SH – to the left
Types of Winds

There are two
main types of
winds: Local and
global winds
Local winds move
over short
distances
Global winds are part
of a pattern of air
circulation
Trade Winds
 In
both hemispheres, the trade
winds blow from the equator to 30
degrees latitude
 Early traders used these winds to
sail from Europe to the America on
“trade routes”
The Doldrums/Horse Latitudes
Where the trades meet from the
Northern and Southern hemisphers at a
low pressure center
 They are named the doldrums because
there is very little wind
 The are also known as the horse
latitudes because this is the area where
ships would get stuck and throw their
horses overboard to save drinking water

Westerlies
 Westerlies
are wind belts in the NH
and SH between 30 and 60
degrees latitude
Polar Easterlies
Wind belts that extend from 60 degrees
latitude to the poles
 Formed from cold sinking air

Jet Streams
 Jet
Streams are narrow belts of
high speed winds that blow in the
upper troposphere
 They often change direction and
can reach speeds of 500 km/hr
 Jet streams DO NOT follow regular
paths around the Earth
Local Winds
 Local
winds are influenced by the
geography of the land
 Shorelines and mountains can
produce local winds