WindsWindsChapter 16 Section 3

Pages 536-544

Chapter 16 Section 3

Pages 536-544

What is Wind?

• Wind- The horizontal movement of air from an area of high pressure to an area of lower pressure.

What causes winds?:

• Winds are caused by differences in air pressure.

• The pressure differences are caused by unequal heating of the Earth’s atmosphere.

• More Dense air sinks– (Air Has High

Pressure)

• Less Dense air rises- – (Air Has Low

Pressure)

What causes winds?:

How is wind measured?

• Weather Vane- an instrument used to determine the direction of the wind.

• Anemometer- An instrument used to measure wind speed.

Anemometer

• Cups blow in the wind and measure the speed of the wind.

Weather Vane

• Tells the direction the wind is blowing from.

• If it is pointing to the south- wind is blowing from the south to the north.

Wind Chill

• Wind Chill Factor- Wind blows over your body and removes body heat away from your body.– The stronger the wind, the more heat

removed, the colder you feel.

• What happens to the temperature as wind speed increases?

• What is the wind chill if the temp is 5˚C and the wind is blowing at 25mph?

Wind Chill

Local Winds

• Are winds that blow over short distances.

• Caused by unequal heating of Earth’s surface with in a small area.– Land heats faster than water.– Water cools slower than land.

• Sea Breeze- The flow of air from a body of water to land.– Land is warmer – less dense air rises.– Water is cooler- more dense air sinks.

Local Winds

• Land Breeze- The flow of air from land to a body of water. – Water is warmer – less dense air rises.– Land is cooler- more dense air sinks.

Local Winds

• A large sea and land breeze over a large region that changes direction with the seasons.– Winds blow steadily from the land to the

ocean, or the ocean to the land depending on the season.

Monsoons

Monsoons (Summer)• The land is warmer

than the water.• Less dense air rises

• The water is cooler than the land.• More dense air sinks

• Wind blows from the water to the land.• Carries water vapor,

making the air humid which causes heavy rain.

Monsoons (Winter)

• The water is warmer than the land.• Less dense air rises

• The land is cooler than the water.• More dense air sinks

• Wind blows from the land to the water.• Causes a dry

season in India.

Reading Wind Maps

Cloud Cover

• The line points into the weather station from the direction the wind came from.• This example shows that the wind is

coming from the east.

Reading Wind Maps

Cloud Cover

• To determine wind speed. Read the flag on the end of the wind direction line.• Use the chart to determine the wind

speeds in knots and mph.• Example above: 8-12 knots (9-14mph)