Transcript 5 Atmospheric Circulation Patterns

Atmospheric Circulation
Patterns
Ally, Molly, Joe
Atmosphere Jigsaw
Pre-assessment (T or F)
• Q: The atmospheric circulation moves only
in vertical motion
• A: False, There are both vertical and
horizontal motions in the atmospheric
circulation Click for answer
• Q: Air moves high pressure areas to lower
pressure areas
• A: True
Click for answer
Wind
• Created by air moving
from high pressure
areas, to lowpressure areas,
where air is less
dense
• Horizontal winds
follow curved
trajectories due to the
rotation of the earth
Sea Breezes
• During day coastal land heats up more than the sea
– Air over land is thus warmed and rises, increasing pressure
– Starts to cool and form clouds
• Air then flows from area of high pressure to lower
pressure over the sea.
• pressure at the surface is higher at sea
– Air then flows in from the sea to the land
• At night, when land cools more quickly than the
ocean, the cycle is reversed
Coriolis Force
• Cause winds that move over long
distances appear to curve
– A force caused by Earth’s Rotation
• Different points on planet move at
different speeds causing air to
move faster in certain areas
• A parcel’s radius of spin around
Earth decreases as it moves
closer to Earth's axis of rotation
– rate of spin increases
• The parcel will deflect to the right
of its original trajectory due to its
high angular velocity
– In Southern hem. parcel would appear
to deflect left
Coriolis Force
• makes winds in low-pressure weather
systems curve into spirals
– Hurricanes
• As air travels, Coriolis force bends its
course toward a state called geostrophic
flow
– pressure gradient force and Coriolis force
exactly balance each other
In the northern hemisphere…

High pressure region
develops pressure force
directed away from the high.
• Air starting to move in response
to this force is deflected to the
right = clockwise circulation
pattern around a region of high
pressure

A low-pressure region
develops, pressure forces air
from outside toward the low.
• Air that moves because of the
force is deflected to the right
and rotates counter-clockwise
around the system.
When wind speed declines…



Air will spiral into low pressure areas near the surface
then rise once they reach the center.
As air rises, it cools, producing condensation, clouds,
and rain.
Air will spiral away from high pressure areas near
surface toward low pressure areas.
– To maintain barometric balance, air will descend from above.


A general circulation of the atmosphere was
presented in 1735 by English meteorologist
George Hadley
Model shows
 warm
air rising over the equator and sinking over the
poles
 simple circulation, upwelling near the equator and
descending in polar regions


in reality circulation ends at a latitude of about 30°
air sinks to the ground and flows back to the tropics

produces easterly winds near surface at low latitudes
and westerly winds at high latitudes
 Farther
north and south, this pattern repeats in two
more sets of circulation zones between tropics and
poles
Post-assessment
• Q: During the day air flows move _______ to _______, at
night it flows ______ to _______
A) the sea to the land; the land to the sea
B) the land to sea; the sea to the land
for answer
A: A) the sea to Click
the land;
the land to the sea
• Q: Because of the Coriolis force, to which direction does air
moving from lower to higher latitude deflect? (in Northern
Hemisphere)
A: to the right Click for answer
• Q: High pressure produces ________ circulation pattern
around the region, whereas low pressure produces
_________ circulation pattern.
Click for answer
A: Clockwise; Counterclockwise
• Q: Which pressure area will result in producing clouds and
rain? High or low?
A: Low pressure
area
Click
for answer