 DMS 6 th Grade Science

 Gravity pulls gas molecules in atmosphere toward Earth, causing air pressure  As altitude ↑, air pressure ↓

 Based on temperature changes  Temperature changes b/c gases absorb solar energy differently

 “turning, changing” layer  Densest atmospheric layer  Almost all Earth’s H 2 O vapor, clouds, air pollution, weather, life-forms  As altitude ↑ the temperature ↓

 “layer”  Home of the ozone layer  As altitude ↑ temperature ↑ b/c ozone absorbs heat energy from sun, (therefore heating up the surrounding area)  Ozone layer protects life on Earth by absorbing UV light

 “middle”  Coldest layer  As altitude ↑ temperature ↓

 “heat”  As altitude ↑ temperature ↑  Ionosphere is here  (NORTHERN LIGHTS, AURORAS)  International Space Station orbits in this layer

DMS 6 th Grade Science

 Naturally occurring form of oxygen in theatmosphere  Consists of three Oxygen atoms instead of two

Abundant between 10-40km above the Earth’s surface “Ozone Layer” contains 90% of atmospheric ozone

Measured through instruments aboard aircrafts and balloons Measured remotely through satellites As science and tools developed, ozone depletion became a recognizable issue First noticed in 1980 in the Antarctic; recently over America and Northern Europe

The ozone provides a thin veil, absorbing ultra violet rays Prevents 97% of UV-B light from reaching earth

Manufactured gases like Chlorofluorocarbons (CFCs) and Halons Refrigerants Fire extinguishers Foams and plastics Aerosol cans Nitrous Oxide (greenhouse gas) 2/3 from natural sources Volcanic eruptions

 Gases are extremely stable, non-flammable, and non- toxic Stability leads to their ability to last a long time in the atmosphere  As UV radiation begins to break them down, chlorine is released and the ozone (O 3 ) turns into oxygen (O 2 )

 Over 24 million km 2 in 1992  Weather conditions of long, dark winters combine with strong wind vortex – the polar stratosphere is isolated  Ice clouds form, providing ideal conditions for the transfer of chlorine into reactive compounds  Suns return in the spring triggers the compounds reaction and the subsequent change of O 3 to O 2

Montreal Protocol (1987) International treaty that called for the rapid phasing out of CFCs and Halon Resulted in substantial drop in production Has made many adjustments in the past 20 years

Tropospheric ozone produced by action of sunlight on the nitrogen oxides and hydrocarbons emitted by fossil fuel gases Called “photochemical reactions” it highly present in large cities with high density of vehicles and frequent sunshine Consequences include eye irritation, headaches, respiratory issues Also toxic to many species of trees, plants, and crops

 Controls on vehicle emissions helping to curb the issue