The Earth’s Atmosphere

ATMOSPHEREIt is the combined gases or

air that surrounds the earth.Atmosphere is very

important for it protects human from the scorching heat of the sun through its ozone layer.

COMPOSITION OF GASES IN THE ATMOSPHERE

LAYERS OF THE ATMOSPHERE

TROPOSPHERE

This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds, rain, snow. Air pressure drops, and temperatures get colder, as you climb higher in the troposphere.

STRATOSPHERE This extends upwards from the

tropopause to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole.

MESOSPHERE

Directly above the stratosphere, extending from 50 to 80 km above the Earth's surface, the mesosphere is a cold layer where the temperature generally decreases with increasing altitude. Here in the mesosphere, the atmosphere is very rarefied nevertheless thick enough to slow down meteors hurtling into the atmosphere, where they burn up, leaving fiery trails in the night sky.

THERMOSPHERE The layer of very rare air above the mesosphere is called the 

thermosphere. High-energy X-rays and UV radiation from the Sun are absorbed in the thermosphere, raising its temperature to hundreds or at times thousands of degrees. However, the air in this layer is so thin that it would feel freezing cold to us Many satellites actually orbit Earth within the thermosphere! 

Ionosphere  Ionosphere is a series of regions in

parts of the mesosphere and thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules. The electrically charged atoms and molecules that are formed in this way are called ions.

It is also in the thermosphere where the aurora borealis or ‘northern lights’ is located most specifically in the northern hemisphere.

The most common aurora colour which is green, is produced by oxygen molecules located about 60 miles above the earth. The rarer red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purple aurora.

The best places to watch the aurora are usually are North America or Europe.

TRANSFER OF HEAT/ENERGY

The motion of atoms and molecules creates heat or thermal energy. All matter has this thermal energy. The more motion the atoms or molecules have the more heat or thermal energy they will have.

CONDUCTION Conduction is the transfer of

heat between substances that are in direct contact with each other. The better the conductor, the more rapidly heat will be transferred.

Metals are good conductors of heat, but non-metals and gases are usually poor conductors. Poor conductors are called insulators.

EXAMPLES OF CONDUCTION:

Touching a stove and being burned Ice cooling down your hand Boiling water by thrusting a red-hot piece of iron into it

CONVECTION Thermal energy is transferred

from hot places to cold places by convection. Convection occurs when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas. Cooler liquid or gas then takes the place of the warmer areas which have risen higher.

EXAMPLES OF CONVECTION:

Hot air rising, cooling, and falling (convection currents)

An old-fashioned radiator (creates a convection cell in a room by emitting warm air at the top and drawing in cool air at the bottom).

Water boiling in a pan The earth's surface is warmed by

the sun, the warm air rises and cool air moves in.

RADIATION Radiation is a method of heat

transfer that does not rely upon any contact between the heat source and the heated object as is the case with conduction and convection. Heat can be transmitted through empty space by thermal radiation often called infrared radiation. This is a type electromagnetic radiation . No mass is exchanged and no medium is required in the process of radiation. 

EXAMPLES OF RADIATION

the heat from the sun heat released from the filament of a light bulb.  Dying clothes in the open air Heat from the sun warming your face Heat from a lightbulb Heat from a fire Heat from anything else which is warmer than its surroundings.

EXAMPLES

QUIZ