Winds Chapter 2 Section 3

What is Wind? Wind is the horizontal movement of air from an area of high pressure to an area of low pressure. Pretty simple huh? How many kinds of winds are there? A bunch!

What Causes Wind? Simply put… All wind is caused by a difference in air pressure. So what causes the differences in air pressure? The cause of differences in air pressure is the uneven heating of Earth’s surface.

How do we measure wind? Two ways: Direction Speed Direction is measured by a wind vane. Wind direction is the direction the wind is blowing from. So a west wind is blowing from the _______. Speed is measured by an instrument called an anemometer.

Wind Chill Factor Increased cooling that wind causes Mainly hear about it during the winter months The stronger the wind the colder it makes you feel. “The temperature will be 25 degrees, but the wind chill will make it feel like 15 degrees.”

Types of Winds Yup, there are different types of wind. Who knew right?

Local Winds Caused by unequal heating of Earth’s surface within a small area Common around large bodies of water How many have been to the lake or beach and the wind is constantly blowing? The surface between land and water are heated unevenly so you get a breeze.

Local Winds Sea Breeze Land Breeze Flow of air from body of water to land Occurs during the day Land heats faster than water Land Breeze Flow of air from land to body of water Occurs during the night Land cools faster than water

Monsoons Monsoon is Arabic for “season” Similar to land and sea breezes EXCEPT they occur over a large area They change direction with the seasons Occurs in South and Southeast Asia Summer-blows towards the land 24/7 and brings rain Winter- blows toward ocean 24/7

Global Winds Winds that blow steadily from a specific direction over long distances Again created by unequal heating of Earth’s surface

Global Convection Currents Occurs because of the temperature differences at the poles and equator Creates a giant convection current Moves air from the equator to the poles

The Coriolis Effect Earth’s rotation affects the way winds move from the poles to the equator Because of Earth’s rotation the winds curve Northern Hemisphere- winds turn toward the right Southern Hemisphere- winds turn toward the left

Global Wind Belts Doldrums Horse Latitudes Occur at and near the equator Winds are either very weak or there is no wind at all Horse Latitudes About 30 degrees north and south Air stops moving toward the poles and sinks Another belt of calm air. What might have happened hundreds of years ago with sailors in this area?

Trade Winds Steady winds found between the equator and 30 degrees north and south latitude Sailors relied upon these winds to carry cargo from Europe to West Indies and South America

Prevailing Westerlies Northern hemisphere blow from the southwest at 30-60 degrees north latitude Southern hemisphere blow from the northwest at 30-60 degrees south latitude Play an important part in the US weather.

Polar Easterlies Cold air sinks and flows back to lower latitudes These meet the prevailing westerlies

Jet Stream About 10km above Earth’s surface are bands of high speed winds Speeds are from 200-400 km/hr Can aid planes when traveling east. Saves time and fuel Hinders planes traveling west Slows them down