SPI 0607.8.2Recognize the connection between the sun’s energy

and the wind.

Characteristics of the Atmosphere

Atmosphere is a mixture of gases that surrounds Earth.

It protects us from the sun’s damaging rays.

The atmosphere is constantly changingbecause of our actions on Earth.

Characteristics of the Atmosphere

78% of Earth’s atmosphere is made up of Nitrogen.

21% is made up of Oxygen.

1% is made up of several different gases like argon and Carbon Dioxide.

Air Pressure

Air pressure is the measure of the force with which air molecules push on a surface.

Like a human pyramid, air pressure increases the close it is to Earth’s surface.

Air Pressure

Layers of the Atmosphere:• There are five layers of the atmosphere:

troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

• They are layered due to the temperature differencesin the atmosphere.

• The troposphere is where we live!• Almost all of the ozone is in the stratosphere

contained in the ozone layer.• The ozone layer protects earth by absorbing some

ultraviolet radiation from the sun.

What is wind?•The movement of air caused by air pressure is called wind.

What causes differences in air pressure?• Differences in air pressure are generally caused by the unequal heating of the earth.

• The equator receives more direct solar energy than other latitudes, so the equator is warmer and less dense.

• Warm, less dense air rises and creates an area of low pressure.

What causes differences in air pressure?• The warm air flows toward the poles.• At the poles, the air is colder and denser, so it sinks.

• As the cold air sinks, it creates areas of high pressure around the poles.

• This cold air then flows toward the equator.

Cold air = blue arrows Warm air = red arrows

Atmospheric Pressure

Pressure Belts & Convection Cells• Air travels in many large, circular patterns called

convection cells. • Convection cells are separated by pressure belts (also

called global winds), which are bands of high pressure and low pressure found at every 30º of latitude.

• Sinking air causes areas of high pressure because sinking air presses down on the air beneath it.

Pressure Belts & Convection Cells

Convection Cells

The Coriolis Effect & Pressure Belts

• Because of the Coriolis Effect in the Northern hemisphere, winds traveling north curve to the east, and winds traveling south curve to the west.

Jet Streams• Jet streams are narrow belts of high-

speed winds that blow the upper troposphere and lower stratosphere.

• They can reach maximum speeds of400 km/h

• They do not follow regular paths around the earth like other global winds.

Jet Streams• Pilots use these to fly somewhere

faster

• Meteorologists use these to track the movement of storms

Jet Streams