DK Eyewitness Weather Book

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DK Eyewitness Weather Book

• Read pages 6 7
• Summarize Reading by writing down 3 facts or
  ideas

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The Atmosphere
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Why we need our atmosphere

• Makes conditions on earth suitable for life!
• Keeps earth warm, but not too warm
• Provides gases necessary for life
• Protects us from dangerous radiation
• Prevents earth from being hit by most meteoroids

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What is air made of?

• 78 Nitrogen
• 21 Oxygen
• A small amount of other gases (examples)
• Argon
• Carbon dioxide
• Neon
• Helium
• Water Vapor

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Properties of Air

• Mass
• Density
• Pressure

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Density of Air

• The amount of mass in a given volume of air
• More molecules of gas greater density
• Less molecules less dense air

Less Dense Less Pressure
More Dense More Pressure
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Air pressure

• The force pushing on an area or surface
• Air pressure is the result of the weight of a
  column of air pushing down on an area

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Measuring Air PressureThe Barometer

• Mercury barometer
• glass tube filled with mercury
• Inches of Mercury ex 30 inHg

• Aneroid barometer means without liquid
• Millibars National Weather Service
• Ex 1016 mb

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Altitude affects Density
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Layers of the atmosphere

• Thermosphere (above 80)
• Exosphere (satellites)
• Ionosphere (aurora borealis)
• Mesosphere (50-80 km)
• Most meteoroids burn up here
• Stratosphere (10-50 km)
• Location of Ozone layer
• Troposphere (0-10 km)
• All weather occurs here

Outer space
Sea Level
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