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Transcript Meteorology

The study of the changes in
temperature, air pressure, moisture,
and wind direction in the
Tuesday, September 20, 2011
• Objectives:
1. Explain the composition, structure, and properties of
Earth’s Atmosphere.
2. Explain the difference between Earth’s Early Atmosphere
and the current Atmosphere.
• Question of the Day:
Can you recall the process that converts water
and sunlight to energy?
The Atmosphere
Mr. Craig’s Earth Science Classroom
The Atmosphere
Mr. Craig’s Earth Science Classroom
Primitive Atmosphere
• Helium and Hydrogen
• After the Moon was formed, it contained
mostly Carbon Dioxide, Carbon Monoxide, and
Water Vapor
• Then---- it was changed when blue-green
algae evolved and emitted oxygen by the
process of photosynthesis.
Thank-you Photosynthesis!!
• If it was not for the earliest forms of life on
Earth, transforming the poisonous primitive
atmosphere into something more suitable,
….we would not
have evolved
The Early Atmosphere
•Much different than our atmosphere today.
•Not suitable for life: No Oxygen to breathe and no Ozone to
protect from sun’s rays.
Mr. Craig’s Earth Science Classroom
The Process
That oxygen
was used to
create Ozone.
Ozone blocked
harmful rays
from the sun
allowing plants
to survive on
Earth’s surface.
Plants produce
allowing you
and I to live
and breathe
on Earth.
Eventually, organisms
called Cyanobacteria
started making Oxygen
Mr. Craig’s Earth Science Classroom
Composition of the Atmosphere
The most abundant gasses in our atmosphere are:
1. Nitrogen
2. Oxygen
3. Argon
Composition of Gasses
4. Carbon Dioxide
Carbon Dioxide
The atmosphere also contains some solids and liquids:
Water Vapor
Mr. Craig’s Earth Science Classroom
Layers of the Atmosphere
Atmosphere is divided into different layers based on temperature.
Temperature changes as you go up.
Sometimes it INCREASES
Sometimes it DECREASES
Sometimes it STAYS THE SAME
Mr. Craig’s Earth Science Classroom
Temperature INCREASES
High temperatures
Thin air.
Feels cold.
Temperature DECREASES
Temperature INCREASES
Contains ozone
O3 absorbs bad rays
Absorption = Warm
Layers of the Atmosphere
Temperature DECREASES.
Weather occurs here.
Mr. Craig’s Earth Science Classroom
The Atmosphere
• Layer of gasses surrounding Earth that is retained
by Earth’s gravity.
3 major Jobs:
1. Protects life from harmful solar radiation
2. Warms Earth’s surface through heat retention
3. Reduces temperature extremes between day
and night
The Atmosphere
• Consists of many gasses:
78% Nitrogen
21% Oxygen
1% Argon
.03% Carbon Dioxide
Layers of the Atmosphere
The “spheres” of the Atmosphere are defined by
their relationship between temperature and
Wednesday, September 21st
• Objective:
– Describe three ways energy is transferred to Earth.
• Question of the Day:
On any given Summer day, the temperature is
higher in downtown Roanoke than at Smith Mountain
Lake. What do you think causes the difference in
Urban Heat Island
urban air and surface temperatures that are higher than
nearby rural areas
The Transfer of Heat Energy
• Earth’s heat source is the Sun.
• Energy from the sun is transferred to Earth’s
surface and the atmosphere.
3 Methods of Heat Transfer
1. Radiation
2. Conduction
3. Convection
• The transfer of heat energy
through electromagnetic waves.
• Most of the solar radiation is
absorbed by the atmosphere
• Much of what reaches the
earth's surface is radiated back
into the atmosphere to become
heat energy.
• Dark colored objects such as asphalt absorb
more of the radiant energy and warm faster
than light colored objects.
• Dark objects also radiate their energy faster
than lighter colored objects.
• ALBEDO- the ability for a surface to reflect
• Albedo- the ability for
a surface to reflect sunlight.
Snow has a very HIGH ALBEDO (85%)
it reflects sunlight very well
Asphalt has a very LOW ALBEDO (5%)
it absorbs sunlight, rather than reflects
• Transfer of energy from one substance to
another within a substance.
Metal- good heat conductor
Air- poor heat conductor
Water- poor heat conductor
• Transfer of heat energy in a fluid
fluid can be a liquid or gas
• Air in the atmosphere acts as a fluid
– As solar radiation reaches the ground, it heats the
rocks, which then heat the air around it and it
forms a bubble of hot air.
– Hot air rises and then is replaced by cooler air
Surface Heating and Air Pressure
• Unequal heating of Earth’s surface CAUSES
differences in Air pressure.
• Differences in Air pressure CAUSES wind!
in Air
Air Pressure
Air pressure is the weight of air pushing down from above.
Weight Pressing Down
As you go up, pressure DECREASES.
Air pressure makes air near Earth’s surface DENSE.
Less Dense
Thin Air
More Dense
Thick Air
The weight of air
above presses air
molecules closer
together near
Earth’s surface.
Mr. Craig’s Earth Science Classroom
Air Pressure
• Despite the tiny size of air molecules and
atoms in the atmosphere, they can exert
a lot of pressure….
in all directions!
Air Pressure
L = Low Pressure
H = High Pressure
Low Pressure
Air pressure is LOWER than the surrounding air
Rising Air
Air cools as it rises
Water molecules condense and form….
clouds, precipitation, and other bad weather
such as tropical storms and cyclones.
High Pressure
an area where the air's pressure is higher than the
pressure of the surrounding air
Descending air
Air warms as it descends
Clouds do not form
FAIR WEATHER… but not always