Chapter 3

Section 1

Seasons and Weather

I. SeasonsA.Earth’s Tilt

1. Earth is tilted at a 23.5° angle relative to the sun.

2. Areas of Earth get more, less direct sun at different times of year.

3. The seasons are related to the earth’s tilt and revolution.

4. The solstice marks beginning of summer, winter.

a. sun’s rays directly overhead at noon at furthest points north and south.

5. The equinox marks the beginning of spring and autumn.

a. day and night are equal in length.

Seaso

ns:

N

ort

hern

H

em

isphere

II.WeatherA.Weather and Climate

1. Weather—atmospheric conditions at a particular location and time.

2. Climate—weather conditions at one location over a long period.

a. Example: Northern Russia has a cold climate

B.What Causes the Weather?1. Sun: amount of solar energy received.

2. Water vapor: determines whether there will be precipitation.

3. Precipitation—water droplets falling as rain, snow, sleet, hail.

4. Cloud cover: clouds may hold water vapor.

C.What Causes the Weather?1. Landforms and bodies of water.

a. Water heats slowly, loses heat slowly.

b. Land heats rapidly, loses heat rapidly.

2. Elevation: as elevation increases, air becomes thinner.

a. Thin air cannot hold moisture.

3. Air movement: distributes moisture and solar energy.

D.Precipitation1.Precipitation comes about when:

a.warm air rises, cools, loses ability to hold water vapor.

b.water vapor condenses into droplets.

c. water droplets form clouds.

d.heavy clouds release droplets as rain, snow.

2.Three types of precipitationa. Convectional

b. Orthographic

c. Frontal

3.Rain shadow—land on leeward side of hills, mountains.a. little precipitation in rain shadow.

Conve

nti

onal

Oro

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phic

Fronta

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E.Hurricanes1. Huge storms called hurricanes, or typhoons in

Asia:

a. form over warm, tropical ocean waters.

b. hit land with heavy rain, high winds, storm surge.

F. Tornadoes1. Tornado—a powerful, funnel-shaped column of

spiraling air:

a. from strong thunderstorms.

b. capable of immense damage.

Look at the typhoons in this image and describe how the wind and water appear to be moving?

5 T

hem

es

Regio

n: To

rnado A

lley

“Tornado Alley” is an

example of a formal region,

which is an area defined by

a limited number or related

characteristics. These

characteristics include

topography and weather

patterns. What type of

precipitation would be most

common in Tornado Alley?

III.Weather ExtremesA.Blizzards

1. Blizzard—heavy snowstorm with strong winds, reduced visibility.

B.Droughts1. Drought: long period of time with either no or

minimal rainfall.

C.Floods1. Water spreads out over normally dry land.

Examine the photograph and guess what economic problems might be caused by the drought?