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The AirThe AirCH 15 Prentice Hall
p.498-501CH 15 Prentice Hall
p.498-501
Around YouAround You
At15
15. 1ppt
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
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