The total amount of rainfall measured by rain – gauge in a certain place in a fixed period of time, which consists of snow, hail and water droplets falling from the clouds. When water vapor present in the atmosphere gets converted into liquid or solid state due to condensation, it is called precipitation. When precipitation occurs in the form of water, it is called rainfall.
When the temperature is less than 0°, rainfall takes place in the form of snow particles, and it is called snowfall. Hail, snow and water all the three can be included under rainfall. The meaning of rainfall is commonly taken from the average rainwater fall. For this, it is necessary to have two things sufficient water vapor content in airand sufficient temperature drop.