Heating of The atmosphere

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Air

The Earth’s Atmosphere

ATMOSPHERE

• From the word ‘atmo’ which means gas or vapor• The layer of gases surrounding the earth• Makes life possible on earth• Gives man air, water, heat, and protects him against

harmful rays of the sun and against meteorites• Consists of 78 percent nitrogen, 21 percent oxygen,

0.93 percent argon , 0.03 percent carbon dioxide and 0.04 percent of other gases.

Layers of the Atmosphere

+Mechanisms of Heat Transfer

• Conduction:– Conduction is the heat transferred through molecular

and electron collisions from one molecule to another.– Metals are good conductors

• Convection:– Convection is the heat transferred via movement or

circulation of a substance, primarily vertically– Warm air rising creates thermal currents.– Advection describes the primarily horizontal

component of convective flow.


• Radiation


• Solar radiation travels through space providing light and heat energy.– Wavelength describes the length of the crest of one

radio wave to the next. – Visible light, often referred to as “white light,” actually

describes the sensitivity of the human eye to a range of wavelengths.

– Infrared radiation cannot be seen by the human eye, but is detected as heat.

– Ultraviolet radiation, on the opposite side of the visible range, consists of wavelengths that may cause sunburns.


• Laws of radiation:1. All objects continually emit radiate energy of a

range of wavelengths.2. Hotter objects radiate more total energy per unit

than colder ones.3. Hotter objects radiate more short wave radiation

than cooler ones.4. Objects that are good absorbers of radiation are

also good emitters.

+ What Happens to Incoming Solar Radiation?

• Reflection:– Light bounces back from an object at the same angle

and intensity.

• Scattering:– Scattering produces a large number of weaker rays

traveling in different directions.

• Backscattering:– Scattering, both backwards and forwards, is known as

backscattering.


• Reflection and the Earth’s albedo:– Albedo is the % of radiation reflected by an object.

• The albedo for Earth is about 30%.• For the moon, the albedo is about 7%.• Light objects have higher albedos and darker objects

have lower albedos.


+


• Diffused light:– Diffused light is the result of dust particles and gas

molecules scatter light in different directions.– This diffusion results in clear days with a bright

blue sky.– A red sun on the horizon is the result of the great

distance solar radiation must travel before it reaches your eyes.

+

The Role of Gases in the Atmosphere• Heating of the atmosphere

– When gas molecules absorb radiation, this energy is transformed into internal molecular motion, detected as a rise in temperature

+The Role of Gases in the Atmosphere


• The greenhouse effect:– The greenhouse effect is a natural phenomenon

and is a result of the Earth’s atmosphere trapping some outgoing radiation.

– Carbon dioxide and water vapor absorb longwave radiation, which heats the air.

– The greenhouse effect is NOT the same as global warming.

+Earth’s Heat Budget

• Annual energy balance:– Incoming and outgoing radiation account for the

Earth’s heat budget.– Figure 2-23 on page 56 (on next slide)

+

+Earth’s Heat Budget

• Latitudinal heat balance:• Balance of incoming and outgoing radiation

applicable for whole earth is not maintained on latitudes. – At 38°, incoming radiation and outgoing radiation are

equal.– Above 38°, the atmosphere loses more radiation.– Below 38°, the atmosphere gains more radiation.

• This energy imbalance is what drives winds and ocean currents.


• Conduction:– Conduction is the heat transferred through molecular

and electron collisions from one molecule to another.– Metals are good conductors

• Convection:– Convection is the heat transferred via movement or

circulation of a substance, primarily vertically– Warm air rising creates thermal currents.– Advection describes the primarily horizontal

component of convective flow.


• Radiation


• Solar radiation travels through space providing light and heat energy.– Wavelength describes the length of the crest of one

radio wave to the next. – Visible light, often referred to as “white light,” actually

describes the sensitivity of the human eye to a range of wavelengths.

– Infrared radiation cannot be seen by the human eye, but is detected as heat.

– Ultraviolet radiation, on the opposite side of the visible range, consists of wavelengths that may cause sunburns.


• Laws of radiation:1. All objects continually emit radiate energy of a

range of wavelengths.2. Hotter objects radiate more total energy per unit

than colder ones.3. Hotter objects radiate more short wave radiation

than cooler ones.4. Objects that are good absorbers of radiation are

also good emitters.


• Reflection:– Light bounces back from an object at the same angle

and intensity.

• Scattering:– Scattering produces a large number of weaker rays

traveling in different directions.

• Backscattering:– Scattering, both backwards and forwards, is known as

backscattering.


• Reflection and the Earth’s albedo:– Albedo is the % of radiation reflected by an object.

• The albedo for Earth is about 30%.• For the moon, the albedo is about 7%.• Light objects have higher albedos and darker objects

have lower albedos.


+


• Diffused light:– Diffused light is the result of dust particles and gas

molecules scatter light in different directions.– This diffusion results in clear days with a bright

blue sky.– A red sun on the horizon is the result of the great

distance solar radiation must travel before it reaches your eyes.

+

The Role of Gases in the Atmosphere• Heating of the atmosphere

– When gas molecules absorb radiation, this energy is transformed into internal molecular motion, detected as a rise in temperature


+Earth-Sun Relationships

• Earth’s two principal motions:– Rotation is the spinning of the earth on its axis,

resulting in the daily cycle of day and night.– Revolution is the movement of the Earth in an

elliptical orbit around sun, producing one year.• Its perihelion, the closest point to sun occurs on about

January 3.• The aphelion, which is the furthest point from sun

occurs on about July 4.

+

+


• What causes the seasons?– The gradual change in day length accounts for

some of the differences in the seasons.– A change in angle of the sun (altitude) also plays a

significant role.

+Earth-Sun Relationship

• When the sun is directly overhead (at 90°) the solar rays are more concentrated and more intense

• The angle of the sun determines the path solar rays take as they pass through the atmosphere– At 90° rays travel the shortest path to the surface– At lesser angles the rays have farther to travel and

more rays get dispersed


• Earth’s orientation

+Earth- Sun Relationship


• Solstices:– The summer solstice occurs on or about June 21 or 22.

• At that time, the sun’s rays are vertical on the Tropic of Cancer. (23 ½° north latitude)

• It also produces the longest day in the northern hemisphere.

– The winter solstice occurs on or about December 21 or 22.• The sun’s rays are then vertical on the Tropic of

Capricorn. (23 ½° south latitude)• This results in the shortest day in the northern

hemisphere.


• Equinoxes:

–Equinox means that day and night are equal. – The autumnal (fall) equinox happens on or about

September 21 or 22.– The vernal (spring) equinox occurs on or about

March 21 or 22.• The sun’s rays are vertical on the equator. (0°)• Earth isn’t tilted away or towards the sun


+Energy, Temperature, and Heat

• Energy is the capacity to do work.• 2 forms of energy:

– Kinetic energy describes an object in motion: the faster the motion, the greater the energy.

– Potential energy means that an object is capable of motion or work. Substances such as food, gasoline, or wood contain potential energy.


• Temperature:– Temperature is a measure of the average kinetic

energy of atoms or molecules in a substance.• As temperature increases, energy is gained.

– Because the particles move faster

• As temperature decreases, energy is lost.


• Heat:– Heat is the energy transferred in or out of object

due to temperature differences.– Energy absorbed but with no increase in

temperature is called latent heat.– Sensible heat is heat we can feel or measure with a

thermometer.


• Earth’s two principal motions:– Rotation is the spinning of the earth on its axis,

resulting in the daily cycle of day and night.– Revolution is the movement of the Earth in an

elliptical orbit around sun, producing one year.• Its perihelion, the closest point to sun occurs on about

January 3.• The aphelion, which is the furthest point from sun

occurs on about July 4.

Troposphere

• The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.

• The troposphere begins at the Earth's surface and extends up to 4-12 miles (6-20 km) high. This is where we live. As the gases in this layer decrease with height, the air become thinner. Therefore, the temperature in the troposphere also decreases with height. As you climb higher, the temperature drops from about 62°F (17°C) to -60°F (-51°C). Almost all weather occurs in this region.

Stratosphere

• Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.

• The Stratosphere extends from the tropopause up to 31 miles above the Earth's surface. This layer holds 19 percent of the atmosphere's gases and but very little water vapor.

Mesosphere

• Meteors or rock fragments burn up in the mesosphere.

• The mesosphere extends from the stratopause to about 53 miles (85 km) above the earth. The gases, including the oxygen molecules, continue to become thinner and thinner with height. As such, the effect of the warming by ultraviolet radiation also becomes less and less leading to a decrease in temperature with height.

Thermosphere

• The thermosphere is a layer with auroras. It is also where the space shuttle orbits.

• The Thermosphere extends from the mesopause to 430 miles (690 km) above the earth. This layer is known as the upper atmosphere.

Exosphere

• The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

• The Exosphere is the outermost layer of the atmosphere and extends from the thermopause to 6200 miles (10,000 km) above the earth. In this layer, atoms and molecules escape into space and satellites orbit the earth. The transition boundary which separates the exosphere from the thermosphere below it is called the thermopause.

Weather

• A local and temporary condition in the air or the atmosphere.

• Heat, moisture and the wind in different combinations produce the different atmospheric conditions known as weather

CLIMATE

Climate

• Associated with place

• Includes daily, seasonal, and yearly variations in the weather

Elements of Climate

1. Temperature- refers to the quantity of heat present n a particular mass.

2. Precipitation- refers to the descent of all forms of moisture from the atmosphere

3. Humidity- refers to the presence of water vapor in the air

4. Atmospheric Pressure- refers to the mass weight of a column of air above a given point

5. Wind- refers to the air in horizontal motion

Factors of Climate1. Latitude

2. Altitude

3. Distribution of Land and Bodies of Water

4. Orographic Barriers

5. Pressure and Wind

6. Ocean Currents

7. Storms

Reference List

www.docudesk.com

Hansen, James R. (Jun 1987). "Chapter Space". Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958. The NASA History Series. sp-4305. United States Government Printing. 12: Hypersonics and the Transition to

www.luc.edu/.../heating-atmosphere.pdf

http://history.nasa.gov/SP-4305/ch12.htm



http://history.nasa.gov/SP-4305/sp4305.htm

http://history.nasa.gov/SP-4305/sp4305.htm




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Heating of The atmosphere