The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space. 1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. 2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun. 3) Meteors or rock fragments burn up in the mesosphere . 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits. 5) The atmosphere merges into space in the extremely thin exosphere . This is the upper limit of our atmosphere. http://www.theozonehole.com/atmosphere.htm
The Ozone Hole October 15,2011 NOAA Antarctic Ozone Hole Reaches Annual Maximum At 25 million square kilometers (about 9.7 million square miles), the ozone hole over the South Pole reached its maximum annual size on September 14, 2011. This year’s hole was the 5th largest on record, as documented by the SBUV/2 sensor on board the NOAA POES spacecrafts.
Greenhouse Gases -Gases in the atmosphere, especially carbon dioxide, water vapor, nitrous oxides, methane and other substances that retain heat.
Burning fossil fuels releases extra carbon dioxide.
Deforestation destroys carbon sinks.
Positive feedback loop - poles covered with ice reflect solar radiation back into space. Now that ice is melting, open water is absorbing more heat, which in turn is melting more ice, leading to more warming.
Monsoon - seasonal reversal of wind patterns caused by differential heating and cooling rates of oceans and continents
Most prevalent in subtropical and tropical areas.
Tilt of Earth’s axis changes location where the Sun is most intense over the course of the year. Places where the Sun shines most directly have evaporation and convection currents which bring thunderstorms.
Seasonal rains support tropical forests and fill great rivers such as Ganges and Amazon.
“ As best as can be determined, the world is now warmer than it has been at any point in the last two millennia, and, if current trends continue, by the end of the century it will likely be hotter than at any point in the last two million years.”-American Geophysical Union
Arctic Sea ice is half as thick as it was 30 years ago, and the ocean area covered by ice has decreased by 1 million sq. km. in 30 yr.
Polar bears are dying as they hunt on pack ice, which is declining.
Antarctic ice shelves are disappearing.
Penguins declined 50% in last 50 yrs.
Alpine glaciers are retreating all over the world.
The oceans are absorbing and storing more heat.
Sea level has risen 15 to 20 cm in last century.
For the first time, data from ESA’s CryoSat mission have been used to map the height of the ice sheet that blankets Antarctica. The preliminary data used here are from February and March 2011. More data still need to be collected to study the ice sheet in detail. Nevertheless, CryoSat's ability to map the edges of the ice sheet is demonstrated by the detail that can be seen of the flow from east Antarctica onto the Ronne-Filchner ice shelf in the west. Orbiting closer to the poles than other Earth observation missions, CryoSat offers additional coverage. The outer white circle represents the limits of earlier missions and the inner circle shows that CryoSat is collecting data up 88° latitude. Credits: CPOM/UCL/ESA/Planetary Visions