properties of the atmosphere
TRANSCRIPT
What is the origin of the Earth’s Atmosphere?
Outgassing Volcanoes as they erupt and release gases Volcanoes release water vapor, carbon dioxide and nitrogen
Most of the water vapor ended up in the oceans. Most of the Carbon Dioxide and Nitrogen ended up in the Atmosphere.
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Properties of the Atmosphere
CO2 + Sunlight + Water = Oxygen + Glucose
It took about 2 Billion years for the atmosphere to change and have Oxygen that we have today
The atmosphere is composed of Nitrogen (78%), Oxygen (21%), and other gases (1%).
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Through evolution, organisms evolved that were able to undergo photosynthesis:
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What is the Structure of the Atmosphere?
Shell of gases that surrounds the earth The atmosphere protects us by blocking out dangerous rays
from the sun. The atmosphere is a mixture of gases that becomes thinner
until it gradually reaches space
Atmosphere is divided into four layers The layers are divided because of changes in temperature Some layers, the temperature is decreasing, some layers
the temperature is increasing. The boundaries (interface) between the layers end in the
suffix “Pause”
Atmosphere
Troposphere The troposphere is the first layer above the surface and
contains half of the Earth's atmosphere Weather occurs in this layer. Stratosphere The temperature rises with altitude. This is caused mainly by the presence of the ozone layer, which absorbs ultraviolet radiation
Many jet aircrafts fly in the stratosphere because it is very stable.
Mesosphere Meteors or rock fragments burn up in the mesosphere. Thermosphere The thermosphere is a layer with auroras. It is also where
the space shuttle orbits. Exosphere The atmosphere merges into space in the extremely thin
exosphere This is the upper limit of our atmosphere.
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Want to go to the Stratosphere?
• https://www.youtube.com/watch?v=0I60Pu869sQ
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Changes in Air Temperature at the Earth’s Surface Changes tend to be cyclic
Two Cycles which control our weather:
Daily weather cycle (cloud cover/weather systems)
Seasons 7
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+1 +0.01+2 +1 +1
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What Causes Air Pressure? Air Pressure •Air exerts a force on the surfaces of ALL objects that it contacts. •AIR PRESSURE is a measure of that force per unit of surface area. •The AMOUNT of air pressure depends on:
–The mass of air molecules –The pull of Gravity –The kinetic molecular activity
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That means that the weight of the atmosphere is exerting on the roof of an average 3 bedroom house 2.1 MILLION Kg or 4.6 MILLION Lbs!!!!
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How much is that? •Average sea-level air pressure is about:
•1.0 kg per square meter, or 14.7 lbs per square inch •Same as 33 ft (10m) of water
How is it really measured? Barometer Instrument that measures air pressure Millibars unit of pressure
On TV or radio, they report it in inches of mercury, which is NOT a unit
of pressure. •Average sea-level air pressure is about: •1013.25 mb or 29.92 in. Hg •Range = 970 – 1040 mb •Lowest EVER = 870 10/12/79 Pacific
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Weather
©Mark Place, 2008-2009 www.LearnEarthScience.com
weather basicsWhere does the energy for weather originate?
the uneven heating
of the Earth’s surface
weather basicsIn the US, the general direction that weather systems
move is toward
FROM the South West
TO the Northeast
(US is between 30 - 45 degrees
Latitude)
Amaze Your Friends!!
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Station Models
Please go to page 13 of the ESRTs
Temperature and dewpoint are measured in
degrees _______F
76
55
.. 138-30\
Temperature
Dewpoint
Wind Direction &
Speed
Barometric Pressure
Current Weather
Cloud Cover
Barometric Trend
Barometric Pressure
138
1013.8
Add a decimal between the last two digits
13.8Add a 9 or 10 in front to fit on the scale
(ranges from 950.0 to 1050.0)
Evaporation Rates
Temperature
Surface Area
Relative Humidity
TemperatureDirect
Relationshipas temperature increases,
the rate of evaporation increases
Surface AreaDirect
Relationshipas surface area increases,
the rate of evaporation increases
Relative HumidityIndirect
Relationshipas the air
becomes more saturated, the rate of
evaporation decreases
What natural process cleans the atmosphere?
Rain
HailSnow
precipitation
Cloud Formation
Warm Air Rises
Expands
Cools to the dewpoint
Clouds are likely to form when:
The air is saturated and rising
The temperature is at the dewpoint
Condensation nuclei are available
the air can hold
As air temperature increases
more water
S l i n g Psychrometer
Dry bulb measures air temperature
Wet bulb temp is lower due to evaporation
Using the charts on page 12 of the ESRTs, calculate the relative humidity and dew point using the following information.
Dry Bulb Wet Bulb Difference Dew Point Relative Humidity (%)
14 10 420 530 1918
6152313
75
12
9555860
Dewpoint Chart RH Chart
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Relative Humidity vs
Air Temperature
Indirect Relationship
as temp increases RH decreases
As dew point increases,
the amount of moisture in the
airINCREASES
As temperature and
dewpoint get closer together,
the probability of precipitationINCREASES
Which has the greatest probability of precipitation?