Download 4.3 WTP Answer key

4.3 Global Winds Reading
Stop and Think
1. If Earth were not rotating, in what directions would you
expect global winds to blow?
Answers will vary, but typically show winds moving
north-south or south-north in the convection cells.
2. How are air masses moving away from the Equator
deflected by Earth’s rotation?
Air masses deflected by Earth’s rotation move to the
right in the Northern Hemisphere and to the left in
the Southern Hemisphere.
3. How can one factor, the Coriolis Effect, cause polar
easterlies that travel from east to west, but also cause
westerlies that travel from west to east?
These winds can also travel from west to east
because the winds that give rise to the polar
easterlies are moving north-south, while the winds
that give rise to the prevailing westerlies are moving
south-north.
4. You read that sailors used the trade winds. What can you
infer about the altitude of the trade winds?
Trade winds are surface winds, not high-altitude
winds.
5. Look again at the summer and winter maps that you
explored in Learning Set 1. In what ways do you think
global winds might be causing the weather patterns you
observed in the data?
The United States is located at the latitudes of the
prevailing westerlies, therefore, their general westeast motion influences both summer and winter
weather in the United States.
4.3 What’s the Point?
Global winds, or winds on a worldwide level, form as a
result of differences in the amount of solar energy
reaching different latitudes. Warm air at the
Equator rises and is replaced by cool, high-pressure air
coming from the North and South Poles. As Earth
rotates, the winds that blow south from the North
Pole are deflected, or bent, by Earth’s rotation so that
they move westward relative to Earth’s surface.
When winds are deflected in this way, the change in
direction is known as the Coriolis effect.
Convection causes the winds to travel north or south.
Those same winds are affected by Earth’s rotation,
which deflects them either west or east, depending on
which way the winds are blowing.
Winds moving away from the poles that are deflected
toward the west produce the winds called the polar
easterlies. Winds moving away from the Equator,
deflected toward the west, produce the trade winds.
Midway between the Equator and the North and
South Poles, high-altitude winds, known as the jet
stream, tend to blow constantly from west to east
around the planet
cool
solar energy
rotates
latitudes
warm
westward
Word Bank
Coriolis Effect
poles
polar easterlies
deflected
trade winds
convection