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Chapter 10
Atmosphere and Air Pressure
Atmosphere and Air Pressure
• The sun provides heat and energy for the
Earth.
• The angle at which sunlight strikes Earth’s
surface is called the angle of insolation.
Seasons
• Seasons are caused by
• The tilt of the Earth on its axis
• The revolution of the Earth around the sun
• The angle of the sun’s rays
Why do some things get hotter
than others?
• Dark colors absorb more heat.
• Light colors reflect more heat.
• Rough textures cause light to bounce
around at many angles absorbing more
energy.
• Rough surfaces get hotter than smooth
surfaces.
• Land absorbs more heat or energy than
water.
What is the Atmosphere?
• Atmosphere is the air that surrounds the
Earth. It reaches from the Earth’s surface
to the edge of space.
Layers of the Atmosphere
• The troposphere is the layer closest to the
Earth’s surface. It is the narrowest layer (8
km to 18km thick). It contains most of the
air in the atmosphere.
• All life exists in the troposphere.
• All weather occurs in the troposphere.
Layers of the Atmosphere
• The layer above the troposphere is the
stratosphere. It is between 18km to 50km.
• The layer above the stratosphere is the
Mesosphere. It is between 50km to 80km.
• The layer above the Mesosphere is the
thermosphere. It is above 80 km high.
How does air pressure change
with altitude?
• Air is a mixture of gases. It is mostly made
up of molecules of nitrogen and oxygen.
• Molecules are the smallest pieces that a
substance can be broken into without
changing what the substance is. They have
mass, so they have weight.
• Air pressure is the force put on a given
area by the weight of the air above it.
• As you go higher in altitude, air pressure
steadily decreases.
What is Weather?
• Weather is what the lower atmosphere, or
troposphere is like at any given place and
time.
• The conditions that make up weather are air
temperature, air pressure, amount of
moisture in the air, wind, clouds, and rain
or snow.
Measuring Weather
• You can measure temperature with a
thermometer.
• Thermometers can use two different
temperature scales. The Celsius scale is
marked with the letter C.
• The Fahrenheit scale is shown by the letter
F.
Measuring Air Pressure
• Air pressure is measured with a barometer.
• Two common types of barometers are the
mercury barometer and the aneroid
barometer.
• In a mercury barometer, air pressure pushes
mercury up in a tube.
• A spring inside an accordion-like metal can
measures air pressure in an aneroid barometer.
*** Read pages D30 – D35 ***