THE ATMOSPHERE
WEATHER:
Weather is defined as the condition of the atmosphere at a specific time and place. The most important characteristic of weather is its changeability. (The ability of the weather to change from cloudy to rainy ,to sunny etc.) It refers to the short term changes in the condition of the atmosphere.
CLIMATE:
Climate refers to the average weather conditions taken over a long period of time ,for example twenty years. The coastal belt of KwaZulu - Natal experiences a sub - tropical climate whilst the south Western Cape experiences a Mediterranean climate.
DEFINITION OF THE ATMOSPHERE:
The atmosphere is a thin layer of air that surrounds the earth. The atmosphere is held to the surface of the earth by the force of gravity.
IMPORTANCE OF THE ATMOSPHERE:
The atmosphere is of vital importance for life on earth. Without the atmosphere, life would be impossible. It gives us air to breathe and protect us from meteorite and ultraviolet rays from the sun. The atmosphere absorbs so much heat that temperatures on earth are such that life is possible. Rainfall occurs by the constant circulation of water to water vapour and vice versa. The cycle causes erosion of the earths surface. Through erosion the outside of the earth changes through the years.
COMPOSITION OF THE ATMOSPHERE:
•The components of the atmosphere may be classified as solid,gas,and liquid.
•The atmosphere is basically a mixture of gases.
•Some of the gases that constitute the atmosphere are nitrogen, oxygen, carbon dioxide, water vapour, ozone, helium and argon.
•The three main gases of the atmosphere are nitrogen (78%),oxygen (21%)and carbon dioxide (0,03%).
•Note that nitrogen and oxygen together comprises 99% of the atmospheric gases.
•The solid components of the atmosphere comprises dust,soot and other pollutants.
•The liquid component comprises water droplets which result from condensation.
IMPORTANCE OF GASES:
•Nitrogen :Essential for plant growth
•Oxygen:Needed for respiration
•Carbon dioxide: Used by plants during photosynthesis to manufacture food.
•Ozone:Absorbs the dangerous ultra - violet rays from the sun.
STRUCTURE OF THE ATMOSPHERE:
The temperature change in the atmosphere with height is not constant. On the basis of temperature change with height ,the atmosphere is divided into four layers,namely, the troposphere, stratosphere, mesosphere and thermosphere.
THE LAYERS OF THE ATMOSPHERE
1.Troposphere
2.Stratosphere
3.Mesosphere
4.Thermosphere
GRAPH SHOWING TEMPERATURE CHANGE IN THE ATMOSPHERE:
TROPOSPHERE:
•It is the lowest layer of the atmosphere.
•The average depth is about 15 kilometers.
•All weather conditions occur in this layer.
•It contains the greatest amount of gases.
•Temperature decrease with the increase in height (positive lapse rate).
•The upper limit of the troposphere is know has the tropopause.
STRATOSPHERE:
•It is the second layer of the atmosphere.
•The average depth is about 40 kilometers.
•The upper limit of the Stratosphere is know has the stratopause.
•Temperature increase with the increase in height (negative lapse rate).
•It contains ozone which absorbs the ultra - violet rays of the sun.
MESOSPHERE:
•It is the third layer of the atmosphere.
•It has an average depth of about 30 kilometres.
•Temperature decrease with an increase in height.
•The upper limit of the mesosphere is know as the mesospause.
THERMOSPHERE
•It is the layer of the atmosphere that is the furthest away from the earth.
•It has an average depth of about 80 kilometres.
This is the end of part 1 of the atmosphere part 2 will be about The ozone layer,Heating of the atmosphere, Isotherms,Isothermal interval, Albedo,Insulation and The green house effect
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