The Atmosphere

The Air Around You What is weather?

The Air Around You Weather is the condition of the atmosphere at a particular time and place.

What is the Atmosphere?

The Air Around You The atmosphere is the layer of gases that surrounds the planet.

Composition of the Atmosphere the atmosphere is a mixture of atoms and molecules of different kinds.

Vocabulary Review: What are atoms and molecules? What is a mixture?

The Air Around You The atmosphere is made up of: Nitrogen Oxygen Carbon Dioxide Other Gases Water Vapor Particles

The Air Around You Nitrogen: about 78% of the atmosphere exists in the form of a nitrogen molecule which consists of 2 nitrogen atoms (N 2 )

The Air Around You Oxygen: about 21% of the atmosphere most oxygen molecules consist of 2 oxygen atoms (O 2 ) Ozone: oxygen molecule that consists of 3 oxygen atoms.

The Air Around You Carbon Dioxide: makes up about 0.04% of the atmosphere. What is the chemical formula for carbon dioxide?

The Air Around You Other Gases: Nitrogen and oxygen make up about 99% of the atmosphere. Argon and Carbon dioxide make up most of the remaining 1%. The rest are called trace gases

The Air Around You Trace Gases: neon (0.001%) helium (0.005%) methane ( ) krypton ( %) hydrogen ( %)

The Air Around You Water Vapor: In what state of matter is water vapor? Water vapor is invisible. What is the chemical formula for a molecule of water?

The Air Around You Particles: air also contains dust smoke salt ?????

The Air Around You The atmosphere is important because: traps the energy of the sun allowing water to exist as a liquid. protects the earth from meteoroids contains the gases that living things need to survive.

Properties of Air Properties of Air Air is made of atoms and molecules which have mass; that means air has mass. because air has mass it also has other properties.

Density measure of the amount of mass in a given volume.

Properties of Air Density = Mass/Volume Units = g/cm 3

Air Pressure: the force pushing on an area or surface.

Properties of Air Air pressure is a result of the column of air above you pushing down. the column of air extends upward through the entire atmosphere.

Denser air has more pressure that less dense air. Why?

Properties of Air Measuring Air Pressure A barometer is used to measure air pressure.

Properties of Air Types of barometers Mercury Barometer Aneroid Barometer

Properties of Air

Units of Air Pressure Inches of Mercury millibars (one inch of mercury equals millibars) Air pressure at sea level is about 76 cm of mercury.

Properties of Air Problem: One inch = 2.54 cm How many inches are there in 76 cm? How many millibars?

Altitude and Properties of Air Altitude the distance above sea level.

What happens to air pressure as altitude increases? Why? What happens to density as altitude increases? Why?

How does altitude affect density?

Layers of the Atmosphere The layers of the atmosphere are determined by changes in temperature

Layers of the Atmosphere The Troposphere: lowest layer of the atmophere Earth’s weather occurs here

Depth: less than 9 km above the north and south poles 16 km above the equator contains almost all of the mass of the atmosphere.

Troposphere continued: as altitude increases temperature decreases with every 1 km increase temperature drops about 6.5 C

Layers of the Atmosphere Troposphere continued: at the top of the troposphere the temperature stops decreasing and stays about -60C.

The Stratosphere extends from the top of the troposphere to about 50 km above the Earth’s surface

Layers of the Atmosphere Stratosphere continued: contains the ozone layer lower stratosphere is about - 60C. the upper stratosphere is warmer the lower stratosphere

Layers of the Atmosphere Mesosphere Meso- means ‘middle’ begins 50 km above Earth’s surface ends at altitude of 80 km

Layers of the Atmosphere Mesosphere continued: is the layer that protects the earth from most meteoroids

Layers of the Atmosphere Thermosphere begins at 80 km no defined out limit Thermo- means ‘heat’

Layers of the Atmosphere Thermosphere continued temperature up to 1800 C why would a thermometer read below 0 C if the thermosphere is so hot?

Layers of the Atmosphere Thermosphere continued is divided into 2 layers: Ionosphere: lower part of the Thermosphere

Layers of the Atmosphere Ionosphere continued 80 km km Northern lights (Aurora borealis) occur here solar energy creates ions of the gas molecules

Layers of the Atmosphere Exosphere exo-means ‘outer’ 400 km outward for 1000’s of km.