THE
ATMOSPHERE
COMPOSITION
Invisible mixture of gases
Nitrogen
& Oxygen most common in lower level
Hydrogen more common in upper atmosphere
Water Vapor & Carbon dioxide in smaller amounts
Other materials
Salt
Rock
particles & dust
STRUCTURE
1st Layer (bottom) : Troposphere
Height
from Earth is 7km to 16 km
Temperature around 65ºF
Air pressure & density decreases as you go up
Tropopause: boundary
2nd Layer Stratosphere
Height
50 km from the troposphere
Temperature 55º F
Upper region contains oxygen (ozone layer)
Absorbs UV radiation
STRUCTURE
Stratopause: Boundary
3rd Layer: Mesosphere
Height from stratosphere is 80 km
Temperature 100º F
meteors burn up in this layer
Mesopause: Boundary
4th layer: Thermosphere
Height from Mesosphere about 500 km
Some space craft orbit here
Absorbs a lot of radiation
Temperature 1000 ºF
Contains ionosphere
Electronically charged particles (ions) are in place by
Earth’s magnetic field
Radio signals can be reflected
STRUCTURE
Thermopause: Boundary
5th Layer: Exosphere
Extends
into outer space
Satellite orbit here
Van Allen belts found here (collects radiation from
sun to protect us)
HEAT TRANSFER IN THE ATMOSPHERE
Radiation: energy that travels in the form of
waves (a wave is a carrier of energy)
Earth
& atmosphere are heated by radiation
Is absorbed or reflected
Wavelength: distance from the crest of one wave
to the crest of another wave
Waves with short wavelengths have more energy
than waves with long wavelengths
HEAT TRANSFER IN THE ATMOSPHERE
Radiant Energy
30
% is reflected back by the atmosphere, clouds &
Earth’s surface
20 % is absorbed by atmosphere
50 % is absorbed by Earth’s surface
The surface cools, long waves of energy are given off
The surface warms, it absorbs long waves of energy
(greenhouse effect)
GREENHOUSE EFFECT
Greenhouse Effect: the rise in temperature that
the Earth experiences because certain gases in
the atmosphere trap energy from the sun.
Without these gases, heat would escape back
into space and Earth’s average temperature
would be about 60ºF colder.
Greenhouse gases: water vapor, carbon
dioxide, nitrous oxide, and methane
Runaway Greenhouse Effect: could cause
melting of glaciers, burns off protective
atmospheric layers, rise in oceans occurs on
planet Venus
WAYS OF MOVEMENT
As radiant energy is absorbed by the earth or
atmosphere, it moves from high concentration
to low concentration
1. Conduction: heat moves from one object to
another while in contact with each other
2. Convection:
heat energy is moved by
a carrier (ex: water, wind)
Convection current:
continuous movement
of air (think of convection
currents in Earth’s
mantle)
DEW POINT
Dew point – temperature to which air must be cooled to
become saturated. (it will rain)
- When relative humidity (amount of moisture in air) is high
dew point is close to air’s temperature.
* Temperature doesn’t need to be lowered much for
saturation.
* If relative humidity is lower; dew point is much less than air
temperature
so need a large decrease in temperature for saturation
THE WATER CYCLE
The water cycle has no starting or ending point
96% of Earth’s water is in the ocean
The Sun drives the water cycle as it heats
Earth’s oceans and rivers
Evaporation: water that is heated turns into a
gas (water vapor) and enters Earth’s
atmosphere
Sublimation: ice and snow
can be directly turned
from a solid into a gas
TRANSPIRATION
The process of evaporation from plants is called
transpiration. (In other words, it’s like plants
sweating.)
CONDENSATION
As water (in the form of gas) rises higher in the
atmosphere, it starts to cool and become a liquid
again. This process is called condensation.
When a large amount of water vapor condenses, it
results in the formation of clouds.
You can see this at home when you take a shower
and the windows and mirrors in the bathroom fog
up. You can also do this by breathing on a mirror.
PRECIPITATION
Precipitation occurs when so much water has
condensed that the air cannot hold it
anymore. The clouds get heavy and water falls
back to the earth.
Forms: rain, hail, sleet or snow
ACCUMULATION
When rain falls on the land, some of the water
is absorbed into the ground forming pockets of
water called groundwater. Most groundwater
eventually returns to the ocean.
Other precipitation runs directly into streams or
rivers. Water that collects in rivers, streams,
and oceans is called runoff.
AQUIFERS!
Runoff, and ground-water seepage, accumulate and are
stored as freshwater in lakes.
Not all runoff flows into rivers, though. Much of it soaks
into the ground as infiltration.
Some water infiltrates deep into the ground and
replenishes AQUIFERS (saturated subsurface rock), which
store huge amounts of freshwater for long periods of
time.
WATER CYCLE
Over time, though, all of this water keeps
moving, some to reenter the ocean, where the
water cycle "ends" ... oops - I mean, where it
"begins."
MORE ON RAIN
Process to form rain.
A. Warm-cloud process
- tiny droplets form by condensation and then grow by
bumping into and combining with other droplets.
- different sizes are more likely to join than same size.
- in the cloud longer, larger droplets.
- larger droplets grow around a large salt nuclei.
( condensation nuclei)
- droplets shrink from evaporation when falling.
MORE ON RAIN
B. Ice process
- in upper layer of clouds
- super cooled water evaporates quickly and
deposits on the ice crystal.
- larger ice crystals get heavy enough, the start to
fall.
- as they fall they will melt with warmer
temperatures.
CLOUDS
Clouds- water droplets and /or pieces of ice
floating in atmosphere.
- most form in troposphere
- indicated direction and speed of wind and
amount of water vapor by shape and position.
*For water to condense from air
1. air must contain water vapor
2. condensation nuclei (dust in air)
3. air temperature must drop to the dew point.
CLOUDS
* Air cools by:
1. Coming into contact with cool surface .
ex. Cold water
2. As heat radiates from it into space.
ex. Fog forms in early morning after clear nights temp.
near ground decreases to dew point.
( fog is cloud near ground)
3. As air rises it cools
ex. Clouds form when air rises to dew point. Causes flat
bases on clouds
Temperature changes occurring without heat – adiabatic
changes.
TYPES OF CLOUDS
Clouds: named by shape.
1.
Cumulus- heaped, fluffy clouds often flat base.
Form- warm air rises, only when temperature falls to dew point.
Found- all altitudes
Shows- fair weather
below 2km and 7km are altocumulus
above 7km are cirrocumulus.
- may extend into atmosphere this forms thunder heads- cumulonimbus
May bring violent weather. (thunder, hail, lightening and tornadoes)
* nimbus or nimbo- cloud is precipitating.
TYPES OF CLOUDS
2. Stratus- spread out where large body air slowly lifted.
- indicate rainy weather
- block sun for long periods of time
below 2km and 7km are altostratus.
above 7km are cirrostratus
* cirrostratus causes a halo around sun or moon.
Nimbostratus- light but steady rain or snow that lasts more than a day.
3. Cirrus- feathery at high altitudes.
thin and wispy
Form- temperature is below freezing- made of ice crystals.
Found- where air is thin
Shows- fair-weather
CLUES TO WEATHER
Cirrus clouds followed by cirrostratus- rainy
period, temperature increases.
Cumulus followed by Cumulonimbus- short
period of heavy rain and temperature
decreases.
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