The Atmosphere

layer of gases that surrounds the planet makes conditions suitable for living things

You probably never think about this but…. What is air? What is it made of? Air is made up of molecules When we breath, we not only breathe in

oxygen, but lots of other gasses, too Air is a mixture of gases held on Earth by

gravity.

OTHER GASES: Water VaporCarbon monoxide (formula CO) Neon (Ne) Oxides of nitrogen Methane (CH4) Krypton (Kr)

Air Pressure Although air molecules are invisible, they still have

weight and take up space. Air pressure is the force exerted on you by the

weight of air molecules JUST LIKE when you are under water you feel the weight of the water around you.

The deeper you go in the ocean, the more pressure you feed - - - the higher you go in the atmosphere the less air molecules and therefore lower pressure.

Air Pressure and Density

The amount of air molecules in a given area determines the air’s pressure

More molecules in a given volume = greater density

Less molecules in a given volume = lower density The higher you are in the air, the less air

pressure The closer you are to the ground, the higher the

air pressure

Where do these gases come from? The Earth’s early atmosphere contained mostly

hydrogen and helium These gases were lost and replaced by gases

from volcanic eruptions, like water vapor and carbon dioxide

Oxygen was created by photosynthetic organisms in the ocean.

The Ozone Layer was created from the conversion of Oxygen molecules from intense sunlight.The Ozone Layer now protects us from harmful UV

rays….ironic!

Why does air stay on the Earth?

The Structure of the Atmosphere The Atmosphere

extends more than 1,000 km or 621 miles above the surface.

There are 4 layers of the atmosphere that are separated by their height above the surface.

The Troposphere is the lowest layer.

Extends 10 km

Contains over 75 percent of all the atmosphere's gases and water and dust.

The sun heats the ground which cause movement in the water vapor and atmospheric gases .This movement causes weather

The warmest part of this layer is at ground level and then it cools towards the upper boundary

The Mesosphere is the next layer above the stratosphere

xtends 50km to 80 km above the ground.

The gases in the mesosphere are too thin to absorb much of the sun's heat.

The temperatures in the mesosphere drop to -184 ºF(-120 ºC)

The Stratosphere extends from the 10-50 km level It has much less “air” molecules and much less water vapor.

This layer contains the ozone layer that absorbs harmful UV rays of the sun.

In the stratosphere higher you get, the warmer the air gets.

The temperature ranges -76 ºF to about 5 ºF

The Mesosphere is the next layer above the stratosphere

xtends 50km to 80 km above the ground.

The gases in the mesosphere are too thin to absorb much of the sun's heat.

The temperatures in the mesosphere drop to -184 ºF(-120 ºC)

The Thermosphere is the next layer

The gases of the thermosphere are very thin.

BUT since they absorb ultraviolet light from the sun

The temperature can rise to 3,600 ºF (2,000 ºC) at the top.

Isn’t planet Earth so nice and warm!

This occurs because the sun heats the Earth’s surface which in turn heats the atmosphere.

The Earth’s surface becomes a radiator!

The Surface of the Earth Snow, ice, water, vegetation, and bare soil all

reflect different amounts of solar radiation back to space. They also heat up at different rates.

For example, dry land heats up rapidly and gives most of that heat back into the atmosphere.

Water temperature changes slowly and stores heat, releasing it over time.

This uneven pattern of surface heating cause changes in pressure and creates wind patterns based upon air pressure.

Sea Breeze

Sea Breeze

Night Breeze (land breeze)

Water in the Atmosphere

The uneven heating of the Earth’s surface produces currents of air that carry water vapor up into the atmosphere and forms clouds.

Warm Air rises and Colder Air sinks creating a cyclic pattern known as the water cycle.