Question: What is pressure? Describe.

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Question of the Day

• Question What is pressure? Describe.
• Answer

Complete Density Matters Lab questions
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Air Pressure

• the force exerted on you by the weight of tiny
  particles of air
• the particles have weight and take up space.

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Why doesn't all that pressure squash me?

• You have air inside your body too
• The air inside your body is pushing out as the
  air outside your body is pushing in.

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How much pressure are you under?

• Earth's atmosphere is pressing against each
  square inch of you with a force of 1 kilogram per
  square centimeter (14.7 pounds per square inch)
  at sea level.
• The force on 1,000 square centimeters (a little
  larger than a square foot) is about a ton!

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Air Pressure

• As your altitude increases the air pressure
  decreases.
• As your altitude decreases the air pressure
  increases.
• This is an inverse relationship!

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Layers of the Atmosphere
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• Barometers are used to measure air in "inches of
  mercury (in Hg) or in "millibars" (mb).
• Air pressure can tell us about what kind of
  weather to expect as well.
• If a high pressure system is on its way, often
  you can expect cooler temperatures and clear
  skies.
• If a low pressure system is coming, then look for
  storms and rain.

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Early Earth Atmosphere

• A dense atmosphere emerged from the vapor and
  gases that were given off as the planet began
  cooling. These gases consisted of
• Hydrogen (H2)
• Water Vapor (H2O)
• Methane (CH4)
• Carbon Oxides (CO2, CO)
• Whats missing?
• Oxygen!
• Early algae and plants eventually changed the
  atmosphere by giving off free oxygen (O2).

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Composition of Air Today

• Nitrogen (N2) 78.084
• Oxygen (O2) 20.9476
• Argon (Ar) 0.934
• Carbon Dioxide (CO2) and other trace elements
  0.0344

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Troposphere

• 90 of content of the atmosphere within 16 km of
  surface
• Most weather occurs here
• Temperature goes down with altitude

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Stratosphere

• Contains ozone layer which plays a major role in
  regulating temperature
• Temperature goes up with altitude

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Ozone Layer

• Found in the Stratosphere
• Ultra-Violet light creates O3 from O2
• Prevents a lot of UV radiation from reaching
  surface
• O3 destroyed by manmade gasses (CFCs)

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Mesosphere

• The mesosphere is characterized by temperatures
  that quickly decrease as height increases.
• With increasing distance from Earth's surface the
  chemical composition of air becomes strongly
  dependent on altitude and the atmosphere becomes
  enriched with lighter gases.

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Thermosphere

• In the thermosphere, temperature increases with
  altitude because molecular oxygen absorbs the
  intense solar radiation.
• Auroras are found
  in this layer

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Exosphere/ Ionosphere

• The outermost layer of the Earth's atmosphere.
• The exosphere is a transitional zone between
  Earth's atmosphere and interplanetary
  space.

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List the first letter of each Layer of the
atmosphere in order. Make a Mnemonic