Earth Science
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Air Movement

Air Movement


Air Movement

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Lesson 15.4: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Convection in the atmosphere creates Earth’s weather.

_____ 2. Water vapor condenses out of air when it is heated.

_____ 3. Water heats up and cools down more slowly than land.

_____ 4. Water has a very low specific heat.

_____ 5. A seasonal land breeze blows during the summer.

_____ 6. Katabatic winds form over high plateaus.

_____ 7. Chinook winds bring moisture to the leeward side of a mountain range.

_____ 8. Santa Ana winds often spread wildfires in Southern California.

_____ 9. You might see dust devils in an haboob.

_____ 10. A Hadley cell forms between 30 and 60 degrees north latitude.

Lesson 15.4: Critical Reading

Name___________________ Class______________ Date________

Read this passage based on the text and answer the questions that follow.

Atmospheric Circulation and Global Winds

Because more solar energy strikes the equator, the air over the equator is warmer than elsewhere on the planet. Warm air has low density, so it rises and forms a low pressure zone. At the top of the troposphere, half of the warm air moves toward the north pole and half toward the south pole along the top of the troposphere. At about 30 degrees north latitude, the air from the equator meets air flowing toward the equator from higher latitudes and descends to the ground, creating a high pressure zone. Once on the ground, the air returns to the equator. These air movements form a convection cell, called a Hadley cell, which is found between 0 and 30 degrees north latitude. A similar Hadley cell is also found between 0 and 30 degrees south latitude, except the air flows in the opposite directions.

In addition to Hadley cells, there are two other major convection cells in each hemisphere. A Ferrell cell is located between 30 and about 60 degrees north or south latitude. In the Northern Hemisphere, air in this cell moves from north to south; it moves in the opposite direction in the Southern Hemisphere. A polar cell is located between about 60 and 90 degrees north or south latitude. In the Northern Hemisphere, the air in this cell moves from south to north and descends at the north pole. It moves in the opposite direction in the Southern Hemisphere and descends at the south pole.

Global circulation cells cause global wind belts. Global wind belts are enormous. They occur because of the flowing air at the bottom of the major circulation cells. In both hemispheres, the global wind belts are the trade winds, westerlies, and polar easterlies. In the Northern Hemisphere, the trade winds flow from northeast to southwest at the bottom of the Hadley cell; the westerlies blow from southwest to northeast at the bottom of the Ferrell cell; and the polar easterlies blow from northeast to southwest at the bottom of the polar cell. The winds blow in the opposite directions in the Southern Hemisphere. The winds do not blow due north or south because of the Coriolis effect. It deflects winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.


  1. Identify and briefly describe the three major convection cells in the Northern Hemisphere.
  2. Identify and describe the three global wind belts in the Northern Hemisphere.
  3. Relate the wind belts in question 2 to the convection cells in question 1.

Lesson 15.4: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

  1. Where cool air descends to the ground there is a
    1. high-pressure zone.
    2. Foehn wind.
    3. valley breeze.
    4. polar front.
  2. Winds blow when air flows from areas of higher to lower
    1. elevation.
    2. pressure.
    3. temperature.
    4. altitude.
  3. When warm air cools it
    1. becomes less dense.
    2. becomes denser.
    3. can hold more moisture.
    4. two of the above
  4. Land and sea breezes
    1. may occur daily and seasonally.
    2. are types of local winds.
    3. occur because of differences in specific heat.
    4. all of the above
  5. India is well known for its local winds called
    1. katabatic winds.
    2. monsoon winds.
    3. Chinook winds.
    4. Santa Ana winds.
  6. A rainshadow occurs
    1. on the leeward size of a mountain.
    2. where moist air sinks to the ground.
    3. in a low-pressure zone.
    4. all of the above
  7. In global atmospheric circulation
    1. warm air sinks at the equator.
    2. warm air flows north from the equator.
    3. warm air flows south from the equator.
    4. two of the above

Lesson 15.4: Matching

Name___________________ Class______________ Date________

Match each definition with the correct term.


_____ 1. wind that blows from a mountain to a valley during the night

_____ 2. wind that blows from land to sea

_____ 3. Hot, dry wind that blows from the interior of California to the Pacific Ocean

_____ 4. wind that is a larger scale version of a land or sea breeze

_____ 5. wind that blows from sea to land

_____ 6. wind that blows where air is forced up over a mountain range

_____ 7. wind that blows from a valley to a mountain during the day


a. land breeze

b. Santa Ana

c. valley breeze

d. Chinook

e. sea breeze

f. mountain breeze

g. monsoon

Lesson 15.4: Fill in the Blank

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

  1. Warm air rising creates a(n) __________ pressure zone on the ground.
  2. The horizontal flow of air through the troposphere is called __________.
  3. A wind called a(n) __________ forms in the downdrafts at the front of a thunderstorm.
  4. Global winds deflect to the east or west because of the __________ effect.
  5. The global winds that blow across most of the continental U.S. are called __________.
  6. Rain is common in a(n) __________ pressure region.
  7. A(n) __________ is a fast-flowing river of air at the boundary between the troposphere and stratosphere.

Lesson 15.4: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Compare and contrast land and sea breezes.