--Cornell Notes
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Ch. 12 The Air Around You and Air Pressure.
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The Air Around You
Weather is the condition of Earth’s atmosphere at a particular time and place. The
gases that surrounds a planet is it’s atmosphere.
Earth’s atmosphere is made up of nitrogen (78%) and oxygen (21%). Carbon
dioxide, water vapor, and other gases make up the last 1%. Earth’s atmosphere
makes conditions on Earth suitable for living things.
Most oxygen molecules have two oxygen atoms. Ozone is a form of oxygen that
has three oxygen atoms in each molecule instead of the usually two.
There is pollution that occurs naturally such as forest fires. Most pollution comes
from the burning of fossil fuels. The burning of fossil fuels can cause smog
(photochemical smog) or acid rain.
Air Pressure
The amount of mass in a given volume of air is its density. Density = mass
volume
A barometer is an instrument that measures air pressure.
Altitude (elevation) is the distance above sea level (level of the surface of the
ocean).
Air pressure decreases as altitude increases. Density will decrease when air
pressure decreases. Density will increase when air pressure increases.
At the top of a mountain, molecules spread out and their air is less dense. At sea
level, the molecules are closer together so the air is denser.
Summary:
Cornell Notes
Topic/Objective: Ch12 sections 3-4
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Layers of the Atmosphere
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Scientists divide Earth’s atmosphere into four main layers:
troposphere, the stratosphere, the mesosphere, and the
thermosphere
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Earth’s weather occurs in the troposphere
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The stratosphere contains the ozone layer.
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The mesosphere protects Earth’s surface from the most
meteoroids
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The outermost layer of Earth’s atmosphere is the
thermosphere
Energy in Earth’s Atmosphere
Summary:
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Most energy from the sun travels to earth in the form of
visible light
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Some sunlight is absorbed or reflected by the atmosphere
before it can reach the surface
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When the Surface is heated, it radiates energy back into
the atmosphere as infrared radiation
Cornell Notes
Topic/Objective: Ch12 sections 5-6
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Heat transfer in the Atmosphere
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Air temperature is usually measured with a thermometer
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Heat is transferred in three ways: radiation, conduction, and
convection
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Radiation, conduction, and convection work together to
heat the troposphere
Energy in Earth’s Atmosphere
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Winds are caused by differences in air pressure
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Local winds are caused by the unequal heating of Earth’s
surface within a small area
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Global winds are caused by the unequal heating of Earth’s
surface over a large area
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Major global Wind belts are the trade winds, the polar
easterlies, and the prevailing westerlies