Chapter 7 Section 6 Winds

Anticipatory Set Have you ever flown a kite? What do you think made the kite fly in the air?

Standards and Objectives S 6.4.e- Students know differences in pressure, heat, air movement, and humidity result in changes in weather. Students will be able to: State how scientists describe and explain winds. Distinguish between local winds and global winds. Identify where the major global wind belts are located.

Language of the Discipline Wind Coriolis effect Anemometer latitude Wind-chill factor jet stream Local wind Sea breeze Land breeze Global wind

What is Wind? Wind- the horizontal movement of air from an area of high pressure to an area of lower pressure. Winds are caused by differences in air pressure. Wind speed is measured with an anemometer. An anemometer has 3 or 4 cups mounted at the end of spokes that spin on an axle. The force of the wind against the cups turn the axle. A meter on the axle shows the wind speed. wind-chill factor- the increased cooling a wind can cause.

Local Winds Local Winds- winds that blow over short distances. Local Winds are caused by the unequal heating of Earth’s surface within a small area. They form only when large-scale winds are weak. ( Ex: a cool breeze blowing in from the water on a hot summer day at the beach, even though there is no wind inland. sea breeze- or a lake breeze, is a local wind that blows from an ocean or lake. land breeze- the flow of air from land to a body of water.

Global Winds Global Winds- winds that blow steadily from specific directions over long distances. Global Winds are created by the unequal heating of Earth’s surfaces. But unlike local winds, they occur over a large area.

Global Winds ( cont.) Coriolis Effect- the way Earth’s rotation makes winds curve. If Earth did not rotate, global winds would blow in a straight line from the poles to the Equator. However, since the Earth rotates, global winds do not follow a straight path. As the winds blow, Earth rotates from east to west underneath them, making it seem as if the winds have curved.

Global Wind Belts ( cont.) Global convection currents and other factors combine to produce a pattern of calm areas and wind belts around Earth. calm areas: doldrums and horse latitudes. major global wind belts: trade winds, polar easterlies, and the prevailing westerlies. latitude- the distance from the equator, measured in degrees.

Global Wind Belts ( cont.) About 10 kilometers above Earth’s surface are bands of high-speed winds called jet streams. Jet stream winds are hundreds of kilometers wide but only a few kilometers deep. They blow from west to east at speeds of 200- 400 kilometers per hour. As jet streams travel around the Earth, they wander north and south along a wavy path.

Checking for Understanding Winds that blow over short distances are called ______________________.

Checking for Understanding Answer: Local Winds

Checking for Understanding What measures wind speed?

Checking for Understanding Answer: an anemometer

Checking for Understanding The increased cooling a wind can cause is called ______________________.

Checking for Understanding Answer: wind-chill factor

Checking for Understanding The way Earth’s rotation makes winds curve is called the ____________________.

Answer: Coriolis effect

Checking for Understanding Winds that blow steadily from specific directions over long distances are called _____________________.

Checking for Understanding Answer: Global Winds