Introduction

• Hydrological cycle is the Continual flow of water between land, sea, and atmosphere, through evaporation, condensation, and precipitation.
• Precipitation is the process of transfer of water either solid or liquid to the earth surface from the atmosphere.

Forms of Precipitation

a) Rain: water droplet size larger than 0.5mm to 6mm (intensity upto 2.5 mm/hr =light rain, 2.5 mm/hr to 7.5mm/hr =moderate rain, > 7.5 mm/hr =heavy rain)

b) Snow: in the form of ice crystal resulting from sublimation chiefly complex hexagonal form

c) Drizzle: fine sprinkler of numerous droplets of size less than 0.5mm and intensity less than 1 mm/hr

d) Hailstone: in the form of lumps of ice , the large downdrafts in mature thunderstorm clouds provide mechanism for hail formation.

e) Sleet: frozen droplets of transparent grain

f) Dew: in clear nights, when the surface of the earth cools due to radiation, the moisture in the atmosphere condenses forming water droplets.