Transcript Guided Notes for Weather Systems

Guided Notes for Weather
Systems
Chapter 12, Section 2
1.
Because the Earth rotates from
west to east, the Coriolis effect
causes moving air particles to
deflect to the right in the northern
hemisphere and to the left in the
southern hemisphere.
2. The Coriolis effect combines with
imbalances in heat to produce
distinct global wind systems that
transport colder air to warmer
areas and warmer air to colder
areas.
3. The trade winds occur at 30
degrees north and south latitude.
There, the air sinks, warms, and
moves toward the equator in a
westerly direction.
4. Near the equator, the trade winds
from both hemispheres converge
and are forced upward, creating an
area of low pressure called the
intertropical convergence zone
(ITCZ).
5. The ITCZ is characterized by a
band of cloudiness and occasional
showers that provide moisture for
tropical rain forests.This area is
also called the doldrums.
6. The prevailing westerlies occur
between 30 and 60 degrees north
and south latitude in a circulation
pattern opposite the trade winds.
In this zone, surface winds move
toward the poles in an easterly
direction.
7. Winds are named for the direction
from which they blow. The
prevailing westerlies are
responsible for the movement of
weather systems across the U.S.
and Canada.
8. The polar easterlies occur
between 60 and 90 degrees
latitude. They flow from the
northeast to the southwest in the
Northern Hemisphere.
9. Narrow bands of fast, highaltitude, westerly winds called jet
streams flow at speeds up to 185
km/h at elevations of 10 to 12 km.
10. Disturbances form along jet
streams and give rise to largescale weather systems that
transport cold air toward the
tropics and warm air toward the
poles.
11. A front is the narrow region
separating two air masses of
different densities. There are four
main types of fronts: cold fronts,
warm fronts, stationary fronts, and
occluded fronts.
Name and describe the 4 types
of fronts




Cold Front: cold air displaces warm air and
forces it to rise, often creating thunderstorms
Warm Front: warm air gradually displaces cold
air, creating clouds and showers
Stationary Front: when two air masses meet,
and neither is displaced, causing long periods
of rain
Occluded Front: when a cold air mass
overtakes a warm front, wedging it upward.
This creates precipitation on both sides of the
front
13. In a surface high-pressure
system, air sinks and spreads
away from the center. This air is
deflected to the right by the
Coriolis effect, making the overall
circulation move in a clockwise
direction in the northern
hemisphere.
14. In surface low-pressure systems,
air rises. This air is replaced by air
from outside of the system, so the
net flow is inward and upward. In
the northern hemisphere, air in a
low-pressure system moves in a
counter-clockwise direction.
15. High-pressure systems are
usually associated with fair
weather, while low-pressure
systems are associated with
clouds and precipitation.
16. A wave cyclone is a type of lowpressure system. It usually begins as a
stationary front. An imbalance causes
part of the front to move south as a
cold front and another part to move
north as a warm front. This sets up a
counter-clockwise, or cyclonic
circulation.