Weather the condition of Earths atmosphere at a particular time and place Atmosphere the envelope of gases that surrounds the planet The Main gases in the Earths Atmosphere 75 Nitrogen ID: 209193
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Slide1Slide2
Important Vocabulary
Weather
– the condition of Earth’s atmosphere at a particular time and place.
Atmosphere
– the envelope of gases that surrounds the planetSlide3
The Main gases in the
Earth’s Atmosphere
~ 75% Nitrogen
21% Oxygen
Less than 1% Carbon Dioxide
Argon makes up most of the other 1%Slide4Slide5
Atmosphere
The atmosphere is a
system
that interacts with other Earth systems.
Events
in one part of the atmosphere
affect other parts
of the atmosphere.Slide6
Air Pressure
Because air has
mass
, it also has other properties, including
density
and
pressure
.
Density
– the amount of mass in a given volume of air D = M/VAir Pressure – the result of the weight of a column of pushing on an area P = F/ASlide7
Instruments to measure air pressure
Barometers
Mercury barometer
Consists of a long glass tube that is
closed
at one end and
open
at another
Aneroid barometer
Aneroid means “without liquid”Has an air tight chamberChamber is connected to a dial by a series of springs and levers.When pressure increases, the thin walls of the chamber are
pushed in. When the pressure drops, the walls bulge out.Slide8Slide9
Units of air pressure
Most weather reports for the public use
inches of mercury
.
(Ex. The air pressure is 30 inches)
The National Weather Service maps indicate air pressure in
millibars
.Slide10
The pressure of the atmosphere is equal to
1 bar (1000
millibars
)
.
1 inch of mercury =
33.86
millibars30 inches of mercury = ~ 1,016 millibarsSlide11
Standard air pressure at sea level is
29.92
inches of mercury. A mercury reading higher than 30.20 inches, with rising or steady pressure generally indicates
fair weather
, becoming cloudy and warmer with rapidly falling pressure. A mercury reading from 29.80 inches to 30.20 inches with rapidly falling pressure means precipitation is coming. A mercury reading under 29.80 inches with rising or steady pressure means it will start to clear and become
cooler
, with slowly falling pressure it is an indication of
precipitation
, and rapidly falling pressure would indicate a
storm.Slide12
Plickers
?
This barometer uses air tight chamber WITHOUT liquid to measure air pressure.
A.) Mercury Barometer
B.) Annathermometer
C.) Aneroid Barometer
D.) All barometersSlide13
Plickers
?
Most of the atmosphere is made up of ____.
A.) Oxygen
B.) Carbon Dioxide
C.) Argon
D.) NitrogenSlide14
Altitude
A.K.A
elevation
, which is the
distance above sea level
Sea level –
average level of the oceans
.
Indiana is about
700 feet above sea level.Air pressure decreases as altitude increases.Analogy - Stack of booksAs air pressure decreases, so does density.Slide15
Altitude continued…
As you go
up
through the atmosphere, the
density of the air decreases.
Density = mass / volume
Air contains
21% oxygen
, whether you are at sea level or on top of a mountain, but since there is more space(volume) at the top of a mountain, the density
decreases. Therefore, the air you breathe at the top of a mountain has fewer oxygen molecules per cubic meter than at sea levelSlide16Slide17
Plickers
?
Where is the atmospheric pressure the greatest?
A.) closest to earth
B.) in the middle of the atmosphere
C.) at a high altitude
D.) closest to spaceSlide18
Layers of the atmosphere
Scientists have divided Earth’s atmosphere in to main layers, which are classified by changes in
temperature
.
Troposphere
Stratosphere
Mesosphere
ThermosphereSlide19
Question
Where is most of the gas in the atmosphere found?
Close to Earth’s surfaceSlide20
Troposphere
Where we
live
Inner
, or lowest layer of Earth’s atmosphere
Tropo
– means
turning or changing
Weather
takes place in this layerAverage thickness is ~ 12 km Shallowest and most dense layerContains almost all the mass of the atmosphereAltitude goes , temperature goes
Water at the top of this layer forms thin, feathery clouds of iceSlide21
Stratosphere
Above troposphere
12km – 50 km
above Earth’s surface
Strato
–
means layer or spread out
Contains
ozone (O3)The ozone layer filters out UV light and absorbs energy from the sun, which warms the air in this layerSlide22
Ozone over timeSlide23
Mesosphere
Meso
– means
middle
50 – 80 km
above the Earth’s surface
Protects Earth’s surface from being hit by
most
meteroidsSlide24
Thermosphere
Outermost layer
80 km
above Earth’s surface
outward into space
No definite outer limit
2 layers
aurora borealis
Ionosphere
exosphereSlide25
Plickers
?
What layer of the atmosphere do we live in?
A.) Troposphere
B.) Stratosphere
C.) Mesosphere
D.) ThermosphereSlide26Slide27
Plickers
?
Which layer means middle layer?
A.) Troposphere
B.) Stratosphere
C.) Mesosphere
D.) ThermosphereSlide28
Plickers
?
Which layer of the atmosphere does weather occur in?
A.) Troposphere
B.) Stratosphere
C.) Mesosphere
D.) ThermosphereSlide29
Energy in Earth’s Atmosphere
Electromagnetic waves – form of energy that can move through the vacuum of space
Most of the energy from the sun travels to Earth in the form of visible light and infrared radiation. A smaller amount arrives as ultraviolet radiation.Slide30
Visible Light
Only part of the spectrum we can see
ROY G BIV
Red
Orange
Green
Blue Indigo VioletSlide31
Radiation – the direct transfer of energy by electromagnetic waves
Infrared radiation is not visible by humans, but can be felt as heat.
The sun gives off ultraviolet radiation.
Ultraviolet radiation can cause sunburns.Slide32
Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface. The rest passes through the atmosphere to the surface.Slide33
Scattering – dispersing light in all directionSlide34
Why is the sky blue?
When you look at the sky, the light you see has been scattered by gas molecules in the atmosphere.
Gas molecules scatter short wavelengths of visible light (B + V) more than long wavelengths (R + O)
Scattered light looks bluer than ordinary sunlight.
That’s why the clear daytime sky looks blue.Slide35
Greenhouse effect
Earth’s surface radiates some energy back into the atmosphere as infrared radiation.
Much of the IR radiation doesn’t immediately travel all the way back into space.
Instead, it is absorbed and held by water vapor, CO
2
, methane, and other gases in the air.Slide36
The greenhouse effect is a natural process. It keeps Earth’s atmosphere at a comfortable temperature
.
Over time, the amount of energy absorbed by the atmosphere and Earth’s surface is in balance with the amount of energy radiated into space.
In this way, Earth’s average temperatures remain fairly constant.Slide37Slide38
Winds
Differences in air pressure cause the air to move.
Wind - the movement of air parallel to Earth’s surface.
Most differences in air pressure are caused by the unequal heating of the atmosphere.Slide39
Measuring wind
Wind direction is determined by a weather vane.
Anemometer – measures wind speed
Windchill
Factor – the increased cooling that a wind can cause
The temp outside is 20 °F, but with a wind speed of 30 mph, the
windchill
factor makes it feel like 1 °
F
Slide40
Local Winds
Winds that blow over short distances are called local winds.
Local winds are caused by the unequal heating of Earth’s surface within a small area.
These winds form only when large scale winds are weak.
2 types of local winds
Sea breezes
Land breezesSlide41
Local vs. Global
Like local winds, global winds are created by the unequal heating of the Earth’s surface.
Unlike local winds, global winds occur over a large area.Slide42
Global winds and the jet stream have an effect on weather and climatic conditions on Earth.
Global winds
are found in each
convection region.
Because
convection cells are in place in the atmosphere and Earth is spinning on its axis, these global winds appear to curve. This is known as the
Coriolis
effect
.
Global winds
MENUSlide43
In the global wind belt regions, the prevailing direction of the winds and how air movement in these large regions affects weather conditions.
The
trade winds
blow from east to west in the tropical region moving warm tropical air in that climate zone.
Global windsSlide44
Doldrums – calm area where warm air rises
Horse latitudes – 2 calm areas of sinking air
Trade winds blow from the horse latitudes toward the equator
Prevailing
westerlies
blow from west to east
Polar easterlies blow cold air away from the polesSlide45
The prevailing
westerly winds
blow from west to east in the temperate region.
The temperate zone temperatures are affected most by the changing seasons, but since the westerly wind belt is in that region, the weather systems during any season move from west to east. Since the United States is in the westerly wind belt, the weather systems move across the country from west to east.
Global windsSlide46
Global Winds
Convection can cause global winds. These winds then move weather systems and surface ocean currents in particular directions.
Due to the spinning of Earth, the weather systems in these regions move in certain directions because the
global wind belts
are set up.Slide47Slide48Slide49Slide50Slide51Slide52
Invention of weather instruments
1500’s Galileo invented water thermometer
1643 Torricelli invented mercury barometer
1667 Hooke invented anemometer
1719 Fahrenheit developed temp scale based on boiling/freezing water
1735 Hadley explained how the earth’s rotation influences winds in tropics
1742 Celsius developed the centigrade temp scaleSlide53
1787 Charles discovered relationship between temp and a volume of air
1835
Coriolis
used math to demonstrate the effect that the earth’s rotation has on atmos. Motions
1869 first isobars were placed on map
1920 concepts of air masses and weather fronts were formulated in Norway
1940’s upper air
ballons
/3-D view of
atmos
1950’s high speed computers1960 Tiros 1 first weather satelliteSlide54