Lesson 5 Our atmosphere and Global Climate Regions
- maintain the same proportion on a constant basis. May have changed over long periods
of time but are relatively the same over recent history. Nitrogen 78%, Oxygen 21%.
–vary in proportion over time
-plants absorb it and release oxygen for us to breathe. CO2 acts like a blanket over the Earth
trapping heat transferred to the atmosphere by the Earth's surface. Fluctuations in carbon dioxide levels in
the atmosphere are thought to be a primary component of major climate change. When carbon dioxide
levels are low, more heat escapes into space and the Earth cools. When carbon dioxide levels are high, in
contrast, more heat is trapped and the Earth warms.
water vapor is vital because it absorbs heat from the Sun. As vapor is moved
around the planet by the currents within the atmosphere, the effect is to moderate temperature making life
possible. The amount of water vapor in the air at any specific location depends upon many variables, but
perhaps the most important is temperature. Warm air can hold more water vapor than cold air.
– found in smaller percentage than water vapor. Made of 3 oxygen atoms when a oxygen
combines with oxygen molecule. Ozone layer is important it keeps 95 – 99% of UV radiation away from
earth. The largest-ever observed ozone depletion hole was seen in September 2006, and measured 10.6
million square miles. Depletion of the ozone layer has been linked to chlorofluorocarbons
- pollutants, dust, volcanic ash released during volcanic eruptions. These reflect solar
radiation and help form raindrops. They can affect our visibility.
Primary air pollutants
are carbon dioxide and water vapor (greenhouse gases), hydrocarbons (acid rain),
carbon monoxide (poisonous to humans) , nitrogen oxide (ground level ozone and acid rain formation),
sulfur oxides ( form acid rain). These are considered status symbol pollutants because in industrial areas.
Major primary solid pollutants – iron, lead , copper, manganese, titanium, nickel, suspended wood
Layers of the atmosphere-
atmosphere extends to 1000km = 600 mi above sea level
– lowest to earth, zone of the biosphere and active weather, containing almost all of the
water vapor in the atmosphere. Earth's surface to between 8 and 18 km (~ 5 to 11 mi.) above sea level. It
is warmed by longwave radiation that is emitted from Earth. The elevation of the upper limit of the
troposphere, the tropopause, depends upon surface temperatures and pressures and so varies with season
and latitude. The troposphere is thicker at the equator than at the poles and also thicker in summer than
winter. Temperature decreases as altitude increases in the troposphere. Change in temp =