Rain is classified according to how it is generated, with three main types of rainfall:

Frontal rain

This is when cold air meets warm air in a ‘weather front’. Warm air rises, so when it bumps into the cold air, it rises above it. However, like when you’re climbing a hill, the higher you go up in the atmosphere, the colder it is. So the warm air that has risen up in the atmosphere now begins to cool down. As a result, the water vapour (a gas) condenses into water (a liquid), forms a cloud, and eventually falls as raindrops.

This type of rain can happen anywhere in the UK, and usually brings grey overcast skies and persistent rain through a large portion of the day.

Orographic rain

When the wind pushes air towards a hill, it is forced upwards, as it cannot go inside the hill. When it reaches the top of the hill it cools down (as the air higher up in the atmosphere is colder), and if it has enough moisture, the water vapour (gas) will condense into water (a liquid) form a cloud and eventually fall as raindrops.

This is why we tend to see more rain on the hills than anywhere else.

Convective rain

This is when the Sun shines on the ground and heats a shallow layer of air close to it. This air is now warmer than the surrounding air, so it rises up in the atmosphere (warm air rises). The higher you go up in the atmosphere, the colder it is. So the warm air that has risen up in the atmosphere now begins to cool down. As a result, the water vapour (a gas) condenses into water (a liquid), forms a cloud and eventually falls as raindrops.

This type of rain is also known as showers and usually produces smaller areas of rain, which is why on some days you may get a downpour, whilst a neighbouring village may have stayed dry. This is the type of situation where you will have rain on and off through the day, with sunshine in between and it seems like the weather cannot make its mind up!

The reason that showers are much smaller in size, and much more unpredictable is because the ground surface varies greatly across the UK. This means the air close to the ground is heated at different rates, which is why the showers can pop up anywhere, and be blown around in different directions by the wind. If, for example, there is tarmac on the ground (a darker surface) this will heat the air more quickly than a lighter surface (such as grass) or one made of water (such as a lake).

Types of Rain

  1. 1. Precipitation •Precipitation is any form of water that falls to the Earth’s surface.
  2. 2. Types of Precipitation • The type of precipitation that falls to the ground depends upon the formation process and the temperatures of the environment between the cloud and the surface
  3. 3. different types of precipitation? • Rain • Snow • Hail • Sleet • Freezing Rain
  4. 4. Rain • Rain develops when growing cloud droplets become too heavy to remain in the cloud and as a result, fall toward the surface as rain
  5. 5. • Rain can also begin as ice crystals that collect each other to form large snowflakes • As the falling snow passes through the freezing level into warmer air, the flakes melt
  6. 6. Rain from snow!
  7. 7. Snow • Snow is formed when ice crystals form from water vapor that is in the clouds directly above your heads! • This process is called sublimation
  8. 8. Hail • Hail is formed when updrafts carry raindrops upwards into extremely cold areas of the atmosphere
  9. 9. Hail • There the raindrops merge and freeze. When the frozen clumps get to heavy they fall to earth
  10. 10. Hail • Hail can vary in size, from the size of a small stone to that of a baseball! So be careful
  11. 11. Sleet • Sleet is frozen raindrops. Sleet begins as rain or snow and falls through a deep layer of cold air that contains temperatures below freezing that exist near the surface.
  12. 12. Sleet • Rain that falls through this extremely cold layer has time to freeze into small pieces of ice
  13. 13. Freezing Rain • Freezing rain is falling rain that cools below 0°C, but does not turn to ice in the air • The water is “supercooled”
  14. 14. Types of rainfall What are the different types of rain and where do they happen?
  15. 15. How it rains 1. Warm air rises 2. Air cools 3. Condensation 4. Clouds form 5. Rain
  16. 16. Types of rainfall There are three types of rainfall: 1. Relief or Topographic 2. Convectional 3. Frontal
  17. 17. 1. Relief Rain 2. Forced to rise over the mountains 1. Warm moist air from the sea
  18. 18. 3. Air cools as it is forced to rise 4. Condensation 5. Clouds form 6. Rain
  19. 19. Relief rain is quite common in Western Ghat where the high land areas are
  20. 20. 2. Convectional Rain 1. The sun heats the ground which heats the air 2. Warm air rises
  21. 21. 4. Air cools as it is forced to rise 5. Condensation 6. Clouds form 7. Rain
  22. 22. Convectional rain is common in the Rajasthan and Plain areas of India in Summer It is also common in Equatorial region of the world along equatorial low pressure belt rgion everyday between 2
  23. 23. Convectional Rainfall
  24. 24. 3. Frontal Rain or Cyclonic 1. Mass of warm air meets a mass of colder air 2. Lighter warm air rises over heavier cold air in the temperate region along Warm and Cold front
  25. 25. 3. Warm air cools 4. Condensation 5. Clouds form 6. Rain
  26. 26. Frontal rain is very common all Temperate regions of the world