Download Chapter 15 – The Atmosphere

Chapter 15 – The Atmosphere
Atmosphere – A mixture of gases composed of 78% nitrogen and 21% oxygen.
Gravity holds the gases close to the Earth making it thicker with higher pressure
near the surface and thinner with lower pressure at higher altitudes.
The Layers of the Atmosphere:
1.
Troposphere – the lowest, densest and closest layer to the surface of the
Earth containing 90% of the mass of the atmosphere.
2.
Stratosphere – the gases in this layer are thin and do not mix. Thin with
very little moisture.
3.
Mesosphere – the coldest layer characterized with a decrease of
temperature with increasing altitude (inverse relationship). This is the
middle layer but also is one of the highest layers.
4.
Thermosphere – one of the highest layers containing too few air
molecules to successfully transfer any thermal energy. Temperatures may
reach 1000°C.
5.
Ionosphere – composed of the upper mesosphere and lower
thermosphere where nitrogen & oxygen atoms absorb harmful solar
radiation. These gas particles become electrically charged (ionized) and
form the auroras when energized by solar particles. This layer also
reflects radio waves back to the surface.
Atmospheric Heating
Energy from the sun reaches the Earth’s surface
in the form of electromagnetic waves called
radiation. Only about two billionths
(2/1,000,000,000,000) of the sun’s energy ever
reaches the Earth’s surface and half of that get
absorbed by the water and land (50%).
Thermal Conduction – The transfer thermal
energy through a conductive material. Similar to
cooking. Heat is transferred from the flame to
the pot to the food.
Convection – The transfer of heat by the
molecules of a liquid or a gas. The movement
created when warm air rises and cold air sinks.
Greenhouse Effect – The warming of the surface and lower
atmosphere caused by water vapor, carbon dioxide, sulfur
dioxide, nitric oxide (greenhouse gases) that absorb radiation
and transfer the thermal energy to the surroundings.
Global Warming – The unnatural, gradual average global
temperature increase due to an increased concentration of
greenhouse gases.
Global & Local Winds:
Wind – The movement of air caused by differences in air
pressure. The greater the pressure differential, the stronger the
wind. Differences in air pressure are caused by the unequal
heating of the Earth’s surface with warm air rising at the
Equator and cooler air sinking at the Poles.
Convection (Hadley) Cells – Large, circular patterns that the air
travels in, separated by high and low pressure belts located
about every 30° latitude.
Coriolis Effect – The curving of the Earth’s winds and ocean
currents caused by the Earth’s rotation.
Global Winds:
Polar Easterlies – Winds that blow from the poles to 60° latitude.
Westerlies – The flow of air to the poles from the west to the east.
This is the opposite of the Trade Winds and blow from 30° to
60° latitude.
Trade Winds – Winds that blow from 30° south latitude to 30°
south latitude. Named by sailor who traveled from Europe to the
Americas.
Doldrums – Located at the Equator where the Trade Winds meet
and rise creating a very calm center of low pressure.
Horse Latitudes – A region located at 30° latitude where the air
sinks creating a high pressure, windless area. Many of the
world’s deserts are located here.
Jet Stream – A narrow band of high altitude, high speed winds
that blow up to 400 km./hr. (240 m.p.h.) in the upper
troposphere and lower stratosphere.
Local Winds – Winds that move air short distances and can blow
from any direction. Can be created by a shoreline, mountain
range or even a forest fire.
Mountain and Valley breezes – Caused by differences in
temperature created by changes in elevation. Valley breeze by
day, mountain breeze by night. Breezes and winds are named
by where they blow from.
Air Pollution – The contamination of the air by pollutants from
human and natural sources. Can cause coughing, headaches
and lung cancers.
Primary Pollutants – put directly from their source directly into
the air. Car exhaust is the #1 human primary pollutant.
Secondary Pollutants – A primary pollutant that reacts with other
pollutants to create a new pollutant such as ozone and smog.
Indoor air pollution is the result of the use of cleaners, heaters,
dirty ductwork, chemicals from carpet, etc. Can be reduced with
a proper ventilation system that mixes household air with
outdoor air.
Acid Precipitation – precipitation that contains acids from air
pollution.
Acidification – Acid precipitation changing the acidity of the
water and soil causing harmful effects.
Acid Shock – A rapid change of the acidity of a body of water
killing fish and damaging eggs of fish and amphibians. Most
harmful in our area with the spring thaw.
Ozone Hole – Harmful effects of chemicals called CFC’s
(chlorofluorocarbons) that are breaking down the ozone (O3)
into oxygen (O2) allowing harmful ultraviolet (UV) radiation to
reach the Earth’s surface.
Cleaning Up Air Pollution:
Allowance Trading System – Limits the amount of pollutants
that a company can release.
Hybrid Cars – Uses both gasoline & electric power.
Scrubbers – Devices that remove some pollutants before they
are released into the air. Usually mounted on the tops of
smokestacks.
Cleaner fuels, catalytic converters, more efficient auto engines,
etc.