16-3 Winds (pages 552–558)

1. State how scientists describe and explain winds.2. Distinguish between local winds and global winds.3. Identify where the major global wind belts are located.

What Is Wind? (page 553)

1. State how scientists describe and explain

winds.

Key Concept: Winds are caused by differences in air pressure.

Wind is the sideways movement of air. The air always moves from an area of

high pressure to an area of low pressure.

Differences in air pressure are caused by differences in how places are heated by

the sun. Warm air has less pressure than cooler air.

The name of a wind tells you where the wind is coming from. For example, a west wind

blows from the west.

Wind speed is measured with an anemometer.

Read each word in the box. In each sentence below, fill in the correct word or words.

a. Wind speed is measured with a(an)

.

b. The sideways movement of air is called

.

Is the following sentence true or false? Air moves from an area of high pressure to an area of low pressure.

Local Winds (page 554)

Key Concept: Local winds are caused by the unequal heating of Earth’s surface within a small area.

w ind anem om eter air pressure

anemometer

wind

Local Winds (page 554)

2. Distinguish between local winds and global

winds.

Key Concept: Local winds are caused by the unequal heating of Earth’s surface

within a small area.

Local winds are winds that blow over a short distance. A cool breeze blowing in

from the water over a beach is an example of a local wind.

Unequal heating often happens near lakes and ocean coasts.

A sea breeze is a local wind that blows from an ocean. A lake breeze is a local

wind that blows from a lake.

A sea breeze or lake breeze usually happens during the day.

A land breeze is a local wind that blows from the land over a lake or ocean. A land

breeze usually happens at night.

Winds that blow over a short distance are called

.

The pictures show two types of local winds. Label the pictures to tell which shows a land breeze and which shows a sea breeze.

a. b.

Global Winds (page 555)

Key Concept: Like local winds, global winds are created by the unequal heating of Earth’s surface. But unlike local winds, global winds occur over a large area.

Warmer air rising

Cooler air moving to take warmer air’s place

Warmer air rising

Cooler air moving to take warmer air’s place

Local winds

Sea breeze Land breeze

Global Winds (page 555)

2. Distinguish between local winds and global

winds.

Key Concept: Like local winds, global winds are created by the unequal heating of Earth’s surface. But unlike local winds,

global winds occur over a large area.

A global wind is a wind that blows steadily over long distances. A global wind blows from the same direction every time.

The sun heats Earth unequally. For example, the sun shines directly over the equator. The sun shines at an angle over the poles.

Earth rotates from east to west. Earth’s rotation makes global winds curve. The

way that winds curve is called the Coriolis effect.

Read the words in the box. In each sentence below, fill in the correct words.

a. The way that winds curve is called the

.

b. A wind that blows steadily over long distances

is called a .

Is the following sentence true or false? The sun

heats Earth unequally.

Global Wind Belts (pages 556–558)

Key Concept: The major global wind belts are the trade winds, the polar easterlies, and the prevailing westerlies.

global wind local wind Coriolis effect

Coriolis effect

Global wind

true

Global Wind Belts (pages 556–558)

3. Identify where the major global wind belts

are located.

Key Concept: The major global wind belts are the trade winds, the polar easterlies,

and the prevailing westerlies.

A series of wind belts circles Earth. Between the winds belts are calm areas.

The trade winds are global winds that blow in the Northern Hemisphere toward the equator from 30° north latitude. Latitude is the distance from the equator.

Winds blow from the west to the east between 30° and 60° latitude in both the Northern and the Southern hemispheres. Since these winds always blow from the west, they are called the prevailing westerlies.

The polar easterlies blow from the poles and curve eastward.

High-speed winds called jet streams blow at the top of the troposphere.

Draw a line from each global wind belt to its correct description.

Global Wind Belt

trade winds

prevailing westerlies

polar easterlies

Description

a. winds that blow from the west to the east between 30° and 60° latitude

b. winds that blow in the Northern Hemisphere toward the equator from 30° north latitude

c. winds that blow from the poles and curve eastward