weather unit atmosphere power point #2

14
What Causes Weather?

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Layers of the atmosphere, wind, and pressure

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Page 1: Weather unit   Atmosphere power point #2

What Causes Weather?

Page 2: Weather unit   Atmosphere power point #2

We should have discovered that land and water do not heat up at

the same rate. If things went correctly, we should know that

land heats up & cools down faster than water. Therefore, the

sun will heat up land quicker than oceans.

Page 3: Weather unit   Atmosphere power point #2

That means that the hot air over land rises and cool air from over the ocean will blow in to take its

place.

Page 4: Weather unit   Atmosphere power point #2

This uneven heating of the Earth causes hot air to rise and cold air to sink, leading to movement of

air in the atmosphere.

Page 5: Weather unit   Atmosphere power point #2

atmosphere

• A blanket of air surrounding the Earth

• made up of gases, water, dust, & other small particles

• It is divided into layers, based on temperature

• troposphere, stratosphere, mesosphere, thermosphere

Page 6: Weather unit   Atmosphere power point #2

Troposphere

• Bottom layer of the atmosphere

• most of Earth’s weather occurs here

• 8 miles thick (13 km)• Supersonic aircraft fly

in this layer

Page 7: Weather unit   Atmosphere power point #2

Stratosphere

• 2nd layer of the atmosphere

• contains the ozone layer

• some aircraft fly in this layer

• 21 miles (50 km)

Page 8: Weather unit   Atmosphere power point #2

Mesosphere

• Third layer of the atmosphere

• coldest layer• this is the layer where

meteors burn up• 50 miles (80 km)

Page 9: Weather unit   Atmosphere power point #2

Thermosphere

• The top layer of the atmosphere

• very high temperatures• gradually merges into

space• 196 miles (320 km)

Page 10: Weather unit   Atmosphere power point #2

Air pressure

• Gravity pulls on air

• lower in the atmosphere means greater air pressure

• cold air is heavier than warm air

• when cold air sinks it forces up warm air

Page 11: Weather unit   Atmosphere power point #2

Wind

• Movement of air• air is constantly

moving • 3 reasons• gravity, temperature,

Earth’s rotation• moves from high to

low or cold to warm

Page 12: Weather unit   Atmosphere power point #2

Local Wind

• A wind that results from a local difference in temperature

• wind blowing in from the sea over a beach during the day

• wind blowing from land to water at night

Page 13: Weather unit   Atmosphere power point #2

Prevailing winds

• Global winds• always blow in the

same direction• caused by uneven

heating of the Earth’s surface and rotation

• creates many circles of air

• moves in curved paths

Page 14: Weather unit   Atmosphere power point #2

????????

• What two factors cause prevailing winds?

• In what layer of the atmosphere does most weather occur?

• In what layer is the ozone layer?

• What drives all weather on the Earth?

• Why is the climate warmer near the equator?