CHAPTER 22 .3

Weather and Climate

Objectives

1. Explain how fronts affect weather2. Explain how climate is different than weather

Key Terms:Air mass, front, climate, topography

http://www.history.com/video.do?name=science&bcpid=1681694258&bclid=1683773457&bctid=1640056921

http://www.history.com/video.do?name=science&bcpid=1681694258&bclid=1683773457&bctid=1640056918

Meteorologists track weather by collecting several types of data

Air masses are large bodies of air throughout which temperature and humidity are similar

Interactions between air masses have predictable effects on local weather

Meteorologists can make predictions about weather based on the characteristics of the air masses

A front is a place where a cold air mass and a warm air mass come in contact

Clouds, wind, and rain can sometimes occur at fronts

On a weather map cold fronts are shown by blue lines with triangles while a warm front is a red line with semicircles

Front types include warm, cold, and stationary

Warm fronts a mass of warm air moves toward and over a slower denser mass of cold air

Nimbostratus clouds are common and can result in steady rain or snow for 1 or 2 days

At a cold front the forward edge of a cold air mass moves under a slower mass of warm air and pushes it up.

Cumulonimbus clouds, high winds, thunderstorms and sometimes tornadoes can accompany this type of front

A stationary front occurs where two air masses meet but neither is displaced

Weather near a stationary front are similar to that of a warm front

Lightning is a discharge of electrical energyIce particles and water droplets move along

the surface of the Earth and build up a charge

The charge can be exchanged between clouds or between a cloud and an object on the Earth’s surface

http://dsc.discovery.com/videos/raging-planet-lightning

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Tornadoes are funnels of high speed wind

Winds of a tornado can be as fast as 310 miles

hrTypically tornadoes start out as water

droplets known as a funnel cloudThe air pressure inside the cloud is

extremely lowThe high pressure on the ground

rushes toward the center creating high winds

These weather occurrences are extremely unpredictable

Hurricanes are large rotating tropical storm systems

The name varies with where they form

These storms start out as tropical depressions, or areas of intense low pressure

Hurricanes are powered by the release of water vapor into precipitation

Although they are extremely slow moving they can cause a lot of damage

Winds can reach 160 miles/hr in the eye wall. In they eye itself winds are calmStorm surge is the main cause of damage in

low lying areasSee demo…

Climate is what we expect, weather is what we get -Mark Twain

Climate is the average weather of a region and is measured over many years

Temperatures tend to be higher closer to the equator because of more concentrated solar energy

The equator is almost always perpendicular to the sun

Earth’s tilt and rotation account for our seasons

The tilt of 23.5 degrees past 90 degrees accounts for our seasons in the fact that one side of the Earth can be tilted toward the sun at any given time

See page 794 for a diagram

The rise and fall of Earth’s surface is known as topography (ever hear of a topographic map?)

Remember how a rain shadow forms? Review this!

See a diagram on page 795

What other land features can effect climate?

List some ways that global climate can change over a long period of time.