Wind: Moving air is called wind.
- Air exerts pressure.
- Air expands on heating.
- Warm air is lighter and rises up.
- Air moves from high pressure to low pressure.
Air Current: Movement of air from high pressure zone to low pressure zone creates air current.
- Uneven heating on land creates air current.
- Air moves from 0-30° north and from 0-30° south towards equator.
- Land gets heated as well as loses heat faster than water.
Monsoon: The flow of air from ocean towards land in summer is called Monsoon or Monsoon wind.
- Monsoon winds carry vapour which falls over the land in the form of rain after cooling down.
- In India harvest is depend on monsoon wind, which brings rain.
- Thunderstorm: Rain with lightning is called thunderstorm. This happens mostly in the summer.
- Thunderstorm occurs frequently in hot and humid tropical areas, such as India.
Cyclone: Fast moving air towards a circle usually with heavy rain is known as cyclone.
- Wind direction, wind speed, humidity and temperature together creates cyclone.
Eye: Centre of cyclone is known as eye.
Tornadoes: Tornadoes are the very fast moving dark cloud in the shape of funnel. Tornadoes may form within cyclones.
- The speed of violent tornadoes may be up to 300km.
- Tornadoes are as destructive as cyclone.
- Anemometer: An instrument which measures the speed of wind.