The AirThe AirCH 15 Prentice Hall

p.498-501CH 15 Prentice Hall

p.498-501

Around YouAround You

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What is Meteorology?

• The study of weather and the atmosphere.– Weather- the condition of

Earth’s atmosphere at a particular time and place.

Earth’s Atmosphere

• Atmosphere is from two Greek words: Atmos and sphaira.

• It makes conditions on the Earth suitable for living things. Contains oxygen and other gases living things need.

• Is constantly changing

Earth’s Atmosphere

• Importance of the atmosphere:– The atmosphere helps

keep the planet warm.• Allows for liquid water.

– Protects from dangerous radiation.

– Burns up chunks of rocks (meteoroids) from space. (meteors)

• Atoms- the smallest unit of a chemical element that can exist in itself.

• Molecules- formed by two or more atoms (elements)– Molecules combine to form

Gases

Composition of Atmosphere

• Contains gases, some of which organisms need to live – Nitrogen– Oxygen– Carbon Dioxide– Water Vapor– Along with other gasses,

particles and liquids.

Composition of Atmosphere

• Most abundant (#1) gas in the atmosphere

• One nitrogen molecule contains 2 nitrogen atoms. N2

• All living organisms need nitrogen in order to grow and repair body cells.

Nitrogen

• Nitrogen fixation must occur to convert N2 into a form that plants can use. (Nitrates)

• Plants absorb the nitrogen from the soil.

• Animals eat the plants.

Nitrogen

• The second most abundant (#2) gas O2

• Oxygen is an important ingredient in the combustion process. – Burning uses oxygen rapidly.– Oxygen reacts slowly with metal

objects to produce rust.

• Ozone –three oxygen atoms O3

– Ozone Layer in Stratosphere

– Ozone Hole

Oxygen

• One molecule has one atom of carbon and two atoms of oxygen.

• Essential to life.– Plants must use CO2 to produce oxygen.

– Animals give off CO2 as a waste product.

Carbon Dioxide

• Fossil fuels increase the amount of CO2 in the atmosphere.

• Earth’s temperature rises as a result.

Carbon Dioxide

• Nitrogen and Oxygen make up 99% of the gases in the atmosphere

• Argon and Carbon dioxide make up most of the remaining 1% (trace gases)

Other (Trace) GasesOther

Gasses

Percent by Volume

Argon 0.93

Carbon Dioxide 0.036

Neon 0.0018

Helium 0.00052

Methane 0.00015

Krypton 0.00011

Hydrogen 0.00005

• Is in the form of a gas.– It is invisible, not the same thing

as steam.

• Varies from place to place.– Desert, Polar Ice Caps• Almost no water vapor.

– Tropical Rain Forest• Five % of the air may be water

vapor

Water Vapor

• Plays an important role in Earth’s weather.

• Forms clouds when water condenses on particles in the air.

• Leads to precipitation

Water Vapor

• Real world air contains tiny solid and liquid particles of:– Dust– Smoke– Salt – Other chemicals

Particles