Download Atmosphere ppt - Bedford Middle School

Meteorology

The study of the atmosphere.
The Atmosphere

The gases that surround the planet
– Much different now than when earth
formed.
– Early atmosphere had no oxygen.
The Atmosphere
New Atmosphere forms: volcanic
eruptions released gases that were
trapped inside the earth.
 Lighter gases (hydrogen) escaped into
space.
 Other gases reacted to form second
atmosphere

The Atmosphere

Importance of water vapor:
– large amounts of water vapor caused
torrential rains
– precipitation collects to form primitive
ocean
– some water vapor split into hydrogen and
oxygen. (Ozone was produced.)
The Atmosphere
Ozone: O3
 Collected at about 30 km from surface.
 Absorbed most of the UV radiation
(harmful).
 Made it possible for life to evolve.

The Atmosphere
Life began in waters.
 Probably bacteria which released
oxygen into the air.
 More oxygen producing organisms
evolved (Plants).
 Some oxygen dissolved into the oceans.

The Atmosphere
Primitive Atmosphere: Carbon dioxide,
Nitrogen, Sulfur dioxide, hydrogen
sulfide, methane, ammonia
 Present Atmosphere: Nitrogen (78%),
Oxygen (21%), Water Vapor, Carbon
dioxide, Helium, Hydrogen, Argon, &
traces of other gases.

Layers of Atmosphere
Troposphere: Closest to Earth
 Most weather takes place here
 Decreases in temperature with elevation
 Tropopause separates troposphere from
next layer

Layers of the Atmosphere
Stratosphere: above troposphere
 temperature rises with altitude due to
ozone absorbing UV radiation &
producing heat.
 Stratopause seperates stratosphere
from next layer

Layers of the Atmosphere
Mesosphere: above stratosphere
 temperature decreases with altitude
due to distance from the earth.
 Mesopause seperates mesosphere from
next layer.

Layers of the Atmosphere
Thermosphere: Outermost layer
 Solar wind can easily pass through the
molecules.
 Collisions increase temperature.
 Temperature increases with altitude.
 Air is very thin
 Contains ionosphere

Layers of the Atmosphere
In the thermosphere, collisions due to
solar wind causes charged particles,
IONS.
 This area is called the IONOSPHERE.
 Causes AURORAS. (northern lights)

Layers of the Atmosphere
Exospere: outermost layer of the
atmosphere
 Extends to outerspace
 Made of a few light gases

Layers of the Atmosphere
DANGER!
Ozone layer is deteriorating due to
chemicals used in refrigerators, air
conditioners, and some aerosol sprays.
 chlorofluorocarbons
 Result may be increase in skin cancer,
cataracts, & reduction in diversity of
living organisms.

Gravity, Weight, & Air Pressure
Gravity: force that pulls the molecules
to the earth. (Strongest near surface.)
 Pressure: the weight caused by gravity
pulling on all the air molecules above an
area. (Strongest near surface)
 Measured by: BAROMETER

Gravity, Weight, & Pressure


Air pressure pushes
down on surface of
mercury in the dish.
Mercury rises in
column.
Gravity, Weight, & Pressure
Air pressure decreases with altitude.
 On Mount Everest, the atmospheric
pressure is less than one-third of what
it is at sea level.

Sun’s energy is transferred to
Earth 3 ways:
Radiation- energy transmitted through
space as waves (electromagnetic
spectrum)
 Conduction – transfer due to molecules
colliding (Must be touching!) A few
centimeters is heated this way.
 Convection – energy transfer by flow of
a heated substance in convection
currents.

Radiation
50% of energy is absorbed by surfaces
(Dark absorbs more; land absorbs faster
than water)
15% absorbed by atmosphere
25% reflected by clouds
6% reflected by atmosphere
4% reflected by earth’s surface.
Convection
Most of the sun’s energy is transmitted
this way.
 Convection currents cause our weather!

Temperature v. Heat
Temperature – measurement of how
fast or slow molecules move. Average
energy of all the moving molecules.
 Measured by thermometer.
 Farenheit, Celsius, Kelvin
 Heat – total amount of energy of all the
molecules.

Dew Point

Temperature to which air must be
cooled to produce condensation. (Can
be called condensation temperature.)

Condensation – gas to liquid
Wind

Horizontal movement of air from high to
low pressure.
High Pressure
Low Pressure
Wind
Relative Humidity
Humidity – amount of water vapor in air
Relative Humidity – ratio of water in air
relative to how much the air can hold.
(expressed as a %)
Warm air can hold more moisture than
cold air.
Measured by a hygrometer (also called a
sling psychrometer).
Cloud Formation
Warm air rises and cools
 Water condenses on condensation
nuclei
 May form when air is forced up because
of a mountain (orographic lifting)
 As air condenses it gives off energy in
the form of latent heat

Cloud Types
Classified by height and shape
 Cirro- High clouds
 Alto- Middle clouds
 Strato- Low clouds
 Cirrus- “hair” wispy, stringy clouds
 Cumulus- “pile or heap” puffy, lumpy
clouds
 Stratus- layer” sheets of clouds
 Nimbus- low, gray rain cloud

Chemical Cycles
Water Cycle: recycles water from earth
to atmosphere.
 Carbon dioxide-Oxygen cycle:
Photosynthesis uses carbon dioxide &
produces oxygen.
 Respiration uses oxygen & produces
carbon dioxide.
 Nitrogen is recycled by bacteria.
