properties of the atmosphere

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

8

+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?