Download Characteristics of the Atmosphere

23.1
 The
atmosphere is a layer of gasses and tiny
particles.
 The study of the atmosphere is called
meteorology.
 Studies weather and climate.
 Weather
is the general condition of the
atmosphere and includes temperature, air
movements, and moisture content.
 The general weather conditions over many
years is climate.
 The
atmosphere is a mixture of chemical
elements and compounds.
 The most abundant are carbon dioxide and
water vapor.
 Water vapor is added to the air by
evaporation that comes from the oceans.
 Moist
air contains as much as 4% water vapor.
 Dry air has less than 1%,
 Ozone is important because it protects the
earth’s inhabitants by absorbing UV rays.
 Ozone has 3 oxygen atoms per molecule.
 Animals
bacteria and plants remove oxygen
from the air as part of their life processes.
 Living things, burning, and weathering would
quickly use up most atmospheric oxygen if it
were not for various processes that add
oxygen to air.
 Land and ocean plants produce large
quantities of oxygen in daylight.
 Oxygen
is released as a product of
photosynthesis.
 The amount of oxygen produced each year
equals that consumed by all processes.
 The amount of oxygen in the air is in a state
of balance and has not changed significantly
over hundreds or thousands of years.
 The
amount of nitrogen in the atmosphere is
maintained through the nitrogen cycle.
 Nitrogen moves from air to the soil, to plants
and animals, and back again to the air.
 Nitrogen is removed by nitrogen-fixing
bacteria.
 The
bacteria change the nitrogen in the air
to a compound in the soil that is vital to the
growth of all plants.
 Animals get nitrogen by eating plants and
then return it to the soil via wastes.
 Due
to the pull of gravity, 99% of the total
mass of atmospheric gasses found within 32
km of the earth's surface.
 There is less air at higher altitude.
 The ratio of the force of the air to the area
of the surface on which it presses is called
atmospheric pressure.
 There
is less pressure at higher altitudes
because there is less air.
 The popping of the ears when driving through
mountains or on a plane is due to the
decreased air pressure on the outside of the
eardrum.
 When pressure equalizes the popping stops.
 An
instrument that measures atmospheric
pressure is called a barometer.
 In a mercurial barometer pressure presses on
the liquid mercury.
 The height varies with atmospheric pressure.
 Standard atmopheric pressure = 760 mm of
mercury or 1 atmosphere.
 The
average atmospheric pressure at sea
level is 1 atmosphere.
 Official weather maps measures air pressure
in millibars (mb).
 One millibar is equal to abouat .001 of
standard atmospheric pressure.
 The
most common barometer used today is
called an aneroid barometer and does not
contain mercury.
 Aneroid means without liquid.
 When the atmospheric pressure increases the
sides of the barometer bend inward.
 An
aneroid barometer can also measure
altitude above sea level.
 When it used for this purpose it is called an
altimeter.
 Special
instruments are needed to record the
temp.
 Have recorded temps of more than 2000 C.
 The lower region, 80 km – 550 km, is called
the ionosphere.
 The layers of ions in this layer can reflect
radio waves back to earth.