Transcript The atmosphere

THE ATMOSPHERE
S6E4a: Demonstrate that land and water absorb
and lose heat at different rates and explain the
resulting effects on weather patterns.
S6E4b: Relate unequal heating of land and water
surfaces to form large global wind systems and
weather events such as tornados and
thunderstorms.
WARM UP: MONDAY
FEBRUARY 10, 2014
What happens to the sun’s
energy once it reaches earth?
LAYERS OF THE ATMOSPHERE
• Objectives:
• Identify the four main layers of the
atmosphere.
• Describe the characteristics of each layer.
4 LAYERS OF THE ATMOSPHERE
• The troposphere
• The stratosphere
• The mesosphere
• The thermosphere
THE TROPOSPHERE
• The lowest layer of the Earth’s atmosphere.
• This is where we live.
• The layer of the atmosphere in which Earth’s weather
occurs.
• Air pressure decreases as you rise in the atmosphere.
• Although the shallowest layer, contains almost all of the
mass of the atmosphere.
• As altitude increases, the temperature decreases.
THE STRATOSPHERE
• The second layer of the atmosphere and contains the
ozone layer.
• Extends from the top of the troposphere to about 50 km.
• The lower stratosphere is cold (about -60 degrees C),
the upper is warmer.
• Why? Because the middle portion contains a layer of
air where there is much more ozone than in the rest of
the atmosphere. When the ozone absorbs energy
from the sun, the energy is converted into heat,
warming the air.
• The ozone layer protects Earth’s living things from
dangerous ultraviolet radiation from the sun.
THE MESOSPHERE
• The 3rd layer of the atmosphere.
• Above the stratosphere
• Marked by a drop in temperature.
• Begins 50km above Earth’s surface and ends 80 km.
• In the outer mesosphere temperatures approach -90
degrees
• The layer of the atmosphere that protects Earth’s
surface from being his by most meteoroids.
THE THERMOSPHERE
• The outermost layer of Earth’s atmosphere
• The air is very thin.
• 80km above Earth’s surface
• No definite outer limit but blends with outer space
• Very hot! Up to 1800 degrees
• Sun strikes the thermosphere first, which causes it to be
so hot.
• Divided into two parts:
• Ionosphere (lower layer)
• Exosphere (outer portion)
ENERGY FROM THE SUN
• Where does the heat in the atmosphere come
from?
• Comes from the sun
• Travels to Earth as electromagnetic waves (a form of
energy that can move through the vacuum of
space)
• These are classified by wavelength
• Radiation: a direct transfer of energy by
electromagnetic waves
ENERGY FROM THE SUN
Most of the energy from the sun
travels to Earth in the form of visible
light and infrared radiation. A small
amount arrives as ultraviolet
radiation.
VISIBLE LIGHT
•Includes all of the colors you see in the
rainbow
•Red, orange, yellow, green, blue,
indigo and violet
•Different colors = different
wavelengths
NON-VISIBLE RADIATION
• Infrared radiation: one form of electromagnetic energy
that has wavelengths that are longer than red light
• Not visible but can be felt as heat
• Ultraviolet radiation: Given off by the sun
• An invisible form of energy with wavelengths that are
shorter than violet waves
• Can cause sunburns, skin cancer and eye damage
ENERGY IN THE ATMOSPHERE
• Some sunlight is absorbed or reflected by the
atmosphere before it can reach the surface. The rest
passes through the atmosphere to the surface.
• Some solar radiation is absorbed in the atmosphere
• Ozone layer absorbs most ultraviolet radiation
• Some sunlight is reflected
• Clouds reflect light back into space
• Scattering: dust particles and gases in the atmosphere
reflect light in all directions – looks bluer than ordinary
light (sky)
ENERGY AT EARTH’S SURFACE
• Some of sun’s energy reaches Earth’s surface and is
reflected back into the atmosphere
• About half is absorbed by the land and water and changed
to heat
• When Earth’s surface is heated, it radiates most of the
energy back into the atmosphere as infrared radiation.
• This is absorbed by water vapor, carbon dioxide,
methane and other gases in the air.
• This energy hats the gases in the air
• Gases form a “blanket” around Earth that holds heat in
the atmosphere – this process is called the greenhouse
effect
HEAT TRANSFER – THERMAL
ENERGY AND TEMPERATURE
• Thermal energy: the total energy of motion in the
particles of a substance
• Air temperature is usually measured with a thermometer
• Thermometer: thin glass tube with a bulb on one end
that contains a liquid
• Temperature is measured in degrees
• Two temperature scales:
• Celsius – freezing 0 degrees, boiling 100 degrees
(scientists use this)
• Fahrenheit scale – freezing 32 degrees, boiling 212
degrees
HOW HEAT IS TRANSFERRED
• Heat: transfer of thermal energy from a
hotter object to a cooler object
• Heat is transferred in three ways within the
atmosphere: radiation, conduction, and
convection
RADIATION
• Direct transfer of energy by
electromagnetic waves
• Ex: warmth of the sun’s rays on your face –
this energy was directly from the sun as
radiation.
CONDUCTION
• The direct transfer of heat from one
substance to another substance that it is
touching
• Ex: spoon in a pot of soup
• Ex: foot on sand on beach
CONVECTION
• The transfer of thermal energy by the movement of a
fluid
• In liquids and gases, particles move easily from one
place to another
• As they move, their energy goes along with them
• Caused by the difference of density
HEATING THE TROPOSPHERE
• Radiation, conduction and convection work together to heat the
troposphere
• During the daytime – sun’s radiation heats the surface
• Land becomes warmer that the air
• Air near surface heated by both radiation and conduction
• Only first few meters of troposphere by conduction
• Air close to ground warmer than a few meters up
HEATING THE TROPOSPHERE
• Troposphere heated mostly by convection
• air near ground heats and spreads
• Cooler, denser air sinks toward surface, forcing the
warmer air to rise
• As the warm air rises and cools, becomes more dense
and sinks where it may be heated once again.
• This forms convection currents – upwards movement of
warm air and the downward movement of cool air
• Convection currents move heat throughout the tropsphere