Chapter Notes and Summary
• An envelope of air surrounding earth is called atmosphere.
• Air is a mixture of gases; consisting of mainly nitrogen (78%) and oxygen (21%), Carbon-dioxide, helium, ozone, argon and hydrogen.
• atmosphere is divided into five layers—troposphere, stratosphere, mesosphere, thermosphere and exosphere.
• Troposphere is layer in which air we breathe exist. Almost all weather phenomenons occur here.
• Weather is atmospheric conditions for a specific time at a specific place.
• Climate is weather conditions for a large period and of a large area.
• Temperature is degree of hotness and coldness of air.
• Temperature is measured in Celsius and Fahrenheit.
• pressure exerted by weight of air on earth’s surface is known as air pressure.
• movement of air from high pressure area to low pressure area is called wind.
• Moisture is water vapour present in air.
• Humidity is moisture in air.
• Precipitation is falling of moisture in form of rainfall, snow, fog, sleet and hailstones.