ankit_grover_61471_assigmanet1

8/3/2019 Ankit_Grover_61471_Assigmanet1

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2010

Flame

Ankit Grover

ASSIGNMENT-1


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1. How did the formation of oceans and the coming of life on the planet affect the

evolution of the atmosphere? What is the existing concentration of the various

gases in the atmosphere?

The Earths atmosphere is a thin, gaseous envelope comprised mostly of nitrogen and oxygen,

with small amount of other gases, such as water vapor and CO2.

First Atmosphere

y Composition - Probably H2, He-The two most abundant gases found in the universe.

y These gases are relatively rare on Earth compared to other places in the universe and

were probably lost to space early in Earth's history because

o Earth's gravity is not strong enough to hold lighter gases

o Earth still did not have a differentiated core (solid inner/liquid outer core) which

creates Earth's magnetic field which deflects solar winds.

y Most scientists believe that this earthly atmosphere escaped into space from earths hot

surface.

Second Atmosphere

Produced by volcanic out gassing.

y Gases produced were probably similar to those created by modern volcanoes (H 2O,

CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 (ammonia) and CH4 (methane)

y No free O2 at this time (not found in volcanic gases).

y Ocean Formation - As the Earth cooled, H2O produced by out gassing could exist as

liquid, allowing oceans to form.

o During this time, large amounts of CO2 were dissolved in oceans. The CO2 got

locked up in carbonated sedimentary rocks.

o Evidence - pillow basalts, deep marine seds in greenstone belts.

Addition of O2 to the Atmosphere


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y Oxygen Production

o Photochemicaldissociation - breakup of water molecules by ultraviolet

2 H2O+UV 2H2+ O2(Depends on competing photochemical reactions)

o Photosynthesis - CO2 + H2O + sunlightorganic compounds + O2

y Oxygen Consumers

o Chemical Weathering - through oxidation of surface materials

o Animal Respiration

o Burning of Fossil Fuels

Components of the Atmosphere Near the Earths Surface:

y Nitrogen Chemical Composition Today - Nitrogen (N2)- 78%, Oxygen (O2)- 21%,

Carbon Dioxide (CO2) - 0.03 %, plus other miscellaneous gases (H2O for one).

2. Describe the various layers of the atmosphere according to their altitude.


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Troposphere: The troposphere is the lowest region in the Earth's (or any planet's) atmosphere.

On the Earth, it goes from ground (or water) level up to about 11 miles (17 kilometers) high. The

weather and clouds occur in the troposphere. Temperature decreases with height at about 6.5

oC per km of ascent, weather occurs in this layer, which extends from the surface to about 12

km

Stratosphere: The stratosphere extends between 11 and 31 miles (17 to 50 kilometers) above

the earth's surface. The earth's ozone layer is located in the stratosphere. Ozone, a form of

oxygen, is crucial to our survival; this layer absorbs a lot of ultraviolet solar energy. Only the

highest clouds (cirrus, cirrostratus, and cirrocumulus) are in the lower stratosphere.

Temperature is initially isothermal (i.e. constant) with height, then increases with height to about

50 km

Mesosphere: The mesosphere extends from between 31 and 50 miles (17 to 80 kilometers)

above the earth's surface. Temperature at Mesosphere decreases with height, to about 80 km

thermosphere; above 80 km, temperature increases once again with height.

Ionosphere: Ionosphere is not actually a layer, but an electrified region where ions and free

electrons exist.

Exosphere: The exosphere is the outermost layer of the Earth's atmosphere. The exosphere

goes from about 400 miles (640 km) high to about 800 miles (1,280 km). The lower boundary of

the exosphere is called the critical level of escape, where atmospheric pressure is very low (the

gas atoms are very widely spaced) and the temperature is very low.

Describe is the vertical temperature profile of the atmosphere?


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Troposphere: Temperature decreases with height at about 6.5 oC (Globally Average)per

km of ascent, weather occurs in this layer, which extends from the surface to about 12

km

Stratosphere: Temperature is initially isothermal (i.e. constant) with height, then

increases with height to about 50 km. It contains Ozone layer, which captures UV rays.

This results in increase in temperature. Temperature in this reason never increases 0 oC.

Mesosphere: temperature decreases with height, to about 80 km thermosphere; above

80 km, temperature increases once again with height

How does atmosphere

Protect the inhabitants of the earth.

y Protects from the most harmful forms of solar radiation: reduces the amount of ultraviolet

y Protects from cosmic radiation.

y Protects from small meteors.


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y Keeps the planet in blanket of air so that the temperature remains within a few degrees

or tens of degrees

y Provides Oxygen to breathe in.

Why does an AM radio station uses less power at night?

The ionosphere region plays a major role in radio communication. The lower part (D-

Region) reflects standard AM radio waves back to earth, but at same time it weakens

them through absorption.

AM radio waves are long enough to interfere with ions in the sun-charged D layer, but at

night the D layer is weak and the AM signal propagates further, requiring stations use

less power.

If you were suddenly placed at an altitude of 100 km above the earth, would you expect

your stomach to expand or contract. Explain

As we know, the pressure decreases when the altitude increases.

Every 1KM increase in altitude results in decrease of 100 mb pressure.

The air inside stomach holds the pressure of the environment when it was in ground level.

Whwn the altitude increases the air pressure of the environment decreases and it becomes

lower than the air pressure inside stomach. Hence the stomach expands in dimension in an

attempt to equalize the pressure.


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