Download The atmospheric layer closest to Earth`s surface

Do you agree or disagree?
1.
Air is empty space.
2.
Earth’s atmosphere is important to living
organisms.
3.
Uneven heating in different parts of the
atmosphere causes global wind patterns
4.
Warm air sinks and cold air rises
5.
Uneven heating in different parts of the
atmosphere causes global wind patterns
6.
Warm air sinks and cold air rises
Vocabulary
Air
• Air is all around us, and although we cannot see it, it
has mass.
• Recall that mass is the amount of matter in an object,
and that matter is anything that has mass and takes
up space.
• Because air has mass, it also has pressure
• Air pressure is the pressure caused by the weight of a
column of air pushing down on an area
The atmosphere
What is the atmosphere?
• The atmosphere is the outermost Earth System of gases
and particles of matter
Why is the atmosphere important?
• The atmosphere is essential to life on Earth:
– contains oxygen and carbon dioxide, and water
necessary for life
– acts like insulation on a house to keep the Earth warm
– protects living organisms from some of the Sun’s
harmful rays
– protects Earth’s surface from being hit by meteoroids
The atmosphere
Layers of the Atmosphere
• The atmosphere has several different layers
• Each layer has unique properties, including
composition of gases and how temperature changes
with altitude
• Altitude is height above sea level
Layers of the
Atmosphere
The atmosphere
The Troposphere
• The atmospheric layer closest to Earth’s surface
• Extends from the face of Earth’s surface to altitudes
between 8 – 15km
• Temperature decreases as you move away from the
surface
• This is the layer where most of Earth’s weather occurs
The atmosphere
The Stratosphere
• The atmospheric layer directly above the troposphere
• Extends from about 15 km to about 50 km
• Contains the ozone layer
• The area of the stratosphere with a high
concentration of ozone
• Due to the ozone layer, temperature increases as
altitude increases within the stratosphere
The atmosphere
The Mesosphere and Thermosphere
• The mesosphere extends from the stratosphere (50 km) to
about 85km
• The thermosphere can extend from the mesosphere to more
than 500 km above Earth’s surface
• Combined these layers are much broader than the
troposphere and stratosphere, yet only 1% of the
atmosphere’s gas molecules are found here
• The ionosphere is a region within the mesosphere and
thermosphere that contains ions
• Between 60 km and 500 km
• The ions in this layer reflect AM radio waves transmitted at
ground level
• Auroras- stunning display of lights in the ionosphere
– Ions from the Sun strike air molecules, causing them
to emit vivid colors of light (can be viewed at higher
latitudes)
The atmosphere
The Exosphere
• The atmospheric layer furthest from Earth’s surface
• Extends from 500 km out to space
– It has no definite end, the molecules here can escape
Earth’s gravity and travel into space
• Pressure and density is so low here that individual gas
molecules rarely strike each other
• Molecules here move at incredibly fast speeds after
absorbing the Sun’s radiation
The atmosphere
Energy in the Atmosphere
• Energy in the form of heat is transferred throughout
the atmosphere
• Recall that there are three types of heat transfer
– Radiation – transfer of heat through space
– Conduction – transfer of heat through direct contact
– Convection – transfer of heat within a fluid/air
• The troposphere is heated mostly through convection
Weather Patterns
Wind
• The horizontal movement of air from an area of high
pressure to an area of low pressure
• Winds are caused by differences in air pressure
• Winds are described by their direction and speed
– The name of a wind tells you where it is coming
from, a south wind blows from the south towards
the north
• Wind direction is determined with a wind vane
• Wind speed is measured with an anemometer
Weather Patterns
Local Winds
• Winds that blow over short distances
• Local winds are caused by the unequal heating of
Earth’s surface within a small area
Global Winds
•
Winds that blow steadily from specific directions over long distances
•
Like local winds they are created by unequal heating of Earth’s
surface, but unlike local winds they occur over a large area
•
Recall that areas near the equator receive the most direct sunlight,
and are therefore warmer than the poles. This difference in
temperature creates giant convection currents
•
Warm air rises at the equator and cold air sinks at the poles,
therefore air pressure tends to be lower near the equator and greater
near the poles
Weather Patterns
The Coriolis Effect
• The change that Earth’s rotation causes in the motion of
objects and that explain how winds curve
• Global winds in the Northern Hemisphere gradually
turn towards the right and in the Southern Hemisphere
winds curve to the left
Weather Patterns
Global Wind Belts
•
Doldrums: areas near the equator with little or no winds; calm areas
where warm air rises
•
Horse Latitudes: areas at 30 degrees north and south of the equator;
calm areas of falling air.
•
Trade Winds: blow from the horse latitudes toward the equator;
generally blow from the northeast in the Northern Hemisphere and
from the southeast in the Southern Hemisphere.
•
Prevailing Westerlies: blow west to east and away from the horse
latitudes; play an important role in the weather of the United States.
•
Polar Easterlies: cold air near the poles sinks and flows back toward
the lower latitudes; blow east to west; major effect on the weather in
the U.S.
•
Jet Streams: bands of high-speed winds about 10 kilometers above
Earth's surface.
Global Wind Belts
Weather Patterns
Air Masses
• Scientists classify air masses according to two
characteristics: temperature and humidity
• Temperature affects air pressure
• Cold, dense air has a higher pressure, while warm, less
dense air has a lower pressure
Types of Air Masses
•
•
•
•
Tropical: warm, form in tropics, low air pressure
Polar: cold, form at the poles, high air pressure
Maritime: humid, form over oceans
Continental: dry, form over land
Weather Patterns
Air Masses
• Air masses are referred to as either maritime or
continental, and as either tropical or polar
–
–
–
–
Maritime Tropical: humid, warm air mass
Maritime Polar: humid, cold air mass
Continental Tropical: dry, warm air mass
Continental Polar: dry, cold air mass
What do you think now?
Agree or Disagree?
1.
Air is empty space.
2.
Earth’s atmosphere is important to living
organisms.
3.
Uneven heating in different parts of the
atmosphere causes global wind patterns
4.
Warm air sinks and cold air rises
5.
Uneven heating in different parts of the
atmosphere causes global wind patterns
6.
Warm air sinks and cold air rises