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.
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