Gaseous envelope surrounding the earth is called atmosphere. Several concentric Layers can be identified in vertical profile of atmosphere. Density, temperature and Composition differ in these layers. Near the earth’s surface, density is highest and with increase in latitude density decreases. Starting from earth’s surface four concentric layers can be distinguished: Troposphere, Stratosphere, and Mesosphere & Thermosphere. Ionosphere has high quantity of ions and free electrons. They help in reflecting the radio waves signaled from surface of earth. Thus they help in long distance Radio-communications. Satellites are stationed at different heights in thermosphere. INSAT-1B was launched from American Space shuttle, Challenger In August 1983, so, we have an exclusive satellite now in geostationary orbit. It is the only operational satellite now in use around the world with a multipurpose capability; the others are all single purpose satellites. Air is being used as medium for aviation transport. It is main transmitting system for the communication of Sound and human voice.
CHARACTERISTICS OF ATMOSPHERE AIR COMPOSITION
Small amount of water vapors, dust, salts, smoke is also found. Movement of air up to height of 100 kms occurs largely and is responsible for Mixing up and making the atmosphere homogeneous. Particular climatic conditions and water cycle in an area is controlled by general circulation of air. Troposphere is peculiar in the sense that it contains much of air. Atmosphere provides oxygen, carbon dioxide and nitrogen to living beings.