Transcript Ch 11 Atmosphere

Atmosphere
An Ocean of Air
Atmospheric Composition
Nitrogen 78%
Oxygen 21%
Other gases 1%
Water vapor 0 - 4.0%
Argon .93%
Carbon Dioxide .03%
Trace gases .01%
• (Neon, Helium, Methane, Krypton, Hydrogen, Ozone,
Xenon)
Water in the Atmosphere
Varies from near zero to four percent
Other gases remain in the same relative
proportions
Water exists in all three states in the
atmosphere
When it changes states it releases or
absorbs energy creating weather
Structure of the Atmosphere
Layers - Troposphere
Contains most of the mass
Weather occurs here
Gradual decrease in temperature
16 km at equator
9 km at the poles
Layers - Stratosphere
Layer of concentrated Ozone
Absorbs Ultraviolet (UV) radiation
Temperature rises with altitude
Heat vs. temperature
Top of the Troposphere to about 50 km
Layers - Mesosphere
Temperature goes down with altitude
No heat absorbing molecules
50 km to about 80 km
Layers - Thermosphere
Temperature goes up with altitude
Molecules are very thin so it would not
feel warm
80 km to about 110 km
Layers - Exosphere
Basically this is the start of outer space
Very few light molecules - Helium and
Hydrogen
Starts at about 110 km (70 miles)
Solar Energy absorption
Solar energy is absorbed by the Earth.
The sun is overhead at 23.5 degrees North at
the summer solstice
The sun is overhead at 23.5 degrees south
latitude at the winter solstice
Some of the Sun’s energy is reflected back
into space. (Clouds 25%, Atmosphere 6%,
Surface 4%)
Some is absorbed and radiated back into
space as infrared energy. (Surface 50%,
Atmosphere 15%)
Energy transfer
Energy is transferred by
Radiation - wave energy emitted
Conduction - heat flows from warm to cold
Convection - currents within an object
Ocean currents bring energy in the form
of heated water to polar latitudes.
Atmospheric wind currents transfer
energy in the form of warm air.
Vertical Temperature
As air rises it cools
Air contains
moisture
At LCL water
condenses and
forms clouds
Air Pressure and Density
Cold air more dense
Cold air has a
higher pressure
Warm air less dense
Warm air has a
lower pressure
Relationships of
temperature and
pressure in the
atmosphere.
Humidity
Humidity is the amount of water vapor in
the air.
Relative humidity is the percent of water
vapor in the air versus the maximum
amount it can hold at a given
temperature.
Classroom practice
Problem solving lab on page 283
More on cloud formation
Clouds form when warm are rises and
hits the LCL (lifted condensation level)
Clouds can also form with orographic
lifting along mountain ranges
Clouds can form at frontal boundaries.
Warm front - warm air overrides cold air
Cold front - cold air pushes warm air up.
Types of Clouds
Cirrus
Cumulus
Stratus
Cirrus Clouds
Cumulus Clouds
Stratus Clouds
Latent Heat of Condensation
Energy is transferred to the gas when
water evaporates
Energy is released when water
condenses (changes from gas to a
liquid)
Allows cumulus cloud air to continue
rising allowing clouds to grow higher