WeatherWater Cycle

Layers of the AtmosphereAir Pressure

Review

Weather is influenced by four key things:

Temperature Moisture Air Pressure Wind

What is weather?

Layers of the Atmosphere

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Keeping Weather DataYou will be completely this sheet daily for the next couple weeks. Good scientists keep good data!

Atmospheric Air Pressure

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Earth’s atmosphere supports life.

The Sun supplies the atmosphere’s energy.

Bill Nye the Science Guy -Atmosphere

http://www.youtube.com/watch?v=gGNxYtT_36I

2 minutes

The atmosphere makes life on E Earth possible.

The atmosphere is a whole layer of air that surrounds Earth. It supports and protects life.

The gases keep Earth warm and transport energy across the planet.

If we did not have an atmosphere, Earth would be a cold, lifeless rock.

The atmosphere is very thin but very important. There is no definite end of the atmosphere, it just

keeps getting thinner and thinner.

Materials in the Atmosphere Most of the materials

in the atmosphere are gases but there are also solid and liquid materials such as dust, sea salt, and water droplets.

The atmosphere mainly contains gasses such as nitrogen, oxygen, and carbon dioxide.

These gases provide materials essential for living things. Nitrogen: promotes

plant growth Oxygen: necessary

for plants and animals

Carbon dioxide: plants use this to make food

Natural processes modify the atmosphere.

The exact amounts of gases in the air can depend on location, time of day, season, ongoing processes, and sudden changes.

Ongoing processes: you breathe in about 3,000 gallons of air a day. When you breath your body exchanges gases with the atmosphere. The air you breath is a slightly different mixture than the air you exhale.

We breathe in air which is a mix of nitrogen, oxygen, and carbon dioxide. So, the air that we breathe out is richer in carbon dioxide and has less oxygen!

Living things take part in a repeated process of gas exchange with the atmosphere.

Cycles: processes like these that repeat over and over.

The Carbon Cycle Carbon dioxide and

Oxygen constantly cycle among plants, animals, and the atmosphere Animals inhale air, use

some oxygen, exhale air that has less oxygen and more carbon dioxide

Plants take in carbon dioxide and release oxygen

The 4 Major Layers of the Atmosphere…

Troposphere Nearest Earth’s surface Weather takes place here!

WE LIVE IN THE TROPOSPHERE!

Stratosphere Clear, dry layer Ozone layer – absorbs

radiation that is harmful to life

Mesosphere Very thin air Less that 0.1% of the mass

of the atmosphere

Thermosphere Less and less dense until it

becomes outer space

The Minor Layers include…OzonosphereIonosphereExosphere

Magnetosphere

What is the Temperature like?

Layers of the Atmosphere RAP

http://www.youtube.com/watch?v=AkaY1dvZer4

The atmosphere’s air pressure changes.

Air exerts pressure.

Air molecules are moving constantly. As they move they are constantly bouncing off other air molecules and surfaces.

Each time it bounces on an object, it pushes or exerts force on that object.

Air pressure – the force of air molecules pushing on an area; the greater the force, the higher the air pressure

The air is being pushed in all directions

Differences in air pressure

Low Pressure When air rises, it leaves behind an area of

lower pressure, because the upward- moving air is not pressing down so hard on the surface.

High Pressure Areas of high pressure

are formed where air is sinking back down, and so pushing down harder.

Changes in air pressure cause changes in the weather.

Pressure is different all over the world.

Lows are areas of low pressure with the lowest pressure at the center.

Lows usually bring wet, cloudy weather.

Highs are areas of high pressure with the highest pressure at the center.

Highs bring sunnier, and dry weather.

The way these move from day to day causes the changes in the weather.

Air pressure is related to altitude and density.

When you hold your hand out by your side, the force of air pressing down on your hand is greater than the weight of a bowling ball. However, we do not feel this force because the same amount of force is pushing up on our hand because air moves in all directions.

Air pressure decreases as you move higher in the atmosphere because you have less air above you.

Air pressure is greater at sea level than it is on top of a mountain. The air is more dense because the air molecules are pushed closer together since there is more pressure.

Air pressure decreases as density decreases.

Pressure and Air Motion

Air pressure can vary at two different locations at the same altitude. For example, when you open a new can of tennis balls you might hear a hissing sound. This is because there is lower air pressure inside the can, and as soon as the can opens, the air around the can moves into the lower pressure areas.

If air pressure was the same around the Earth, the atmosphere wouldn’t move much. Because there are differences in pressures, air is constantly moving. High pressure areas are moving towards low pressure areas.

Measuring Air pressure

Barometer – an instrument that measures air pressure

In some cases, there are instruments that have a chamber to measure the air pressure. When the pressure is high, the chamber contracts. When the pressure is low, the chamber expands. Depending on how much it contracts or expands, a needle will point to a certain air pressure.