DMS 6th 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 H2O 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 6th Grade Science

Naturally occurring form of oxygen in the atmosphere

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 (O3) turns into oxygen (O2)

Over 24 million km2 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 O3 to O2

•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