The process of precipitation

The concept/process of precipitation is easy to follow. Moisture carrying air is forced to rise by heating or by an obstacle on the wind path.

According to USGS, Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth. Most precipitation falls as rain.

The risen air expands and cools to dew point temperature. The moisture in the air then condenses, usually around dust and smoke particles, to form water particles ( if ordinarily cooled) or ice crystals (if super cooled). It is these particles that constitute the clouds. The water droplets or ice crystals then coalesce and become so heavy that they can no longer remain suspended in the atmosphere. So they fall as precipitation.
Three factors: heating of the earth surface, obstacle caused by either relief or a mass of cold air triggers the rise, and they produce three types of precipitation which are

• Convectional precipitation
• Orographic precipitation
• Frontal precipitation

Convectional precipitation
When the ground surface is heated by the sun, the air over it is heated, becomes light and rises. The rainfall process is set in motion, and precipitation that results is called convectional precipitation. Convectional precipitation is of short duration and limited to an area of 50kmsq. it is common i n the tropics. It is also found in temperate continental interiors, particularly in summer, and it occurs mostly in late afternoons.

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Orographic precipitation
When an onshore wind which has picked up more water vapour from the ocean strikes on a coastline, or trees, or any highland, it is forced to rise in trying to scale over this obstacle. The process of precipitation is once more set in motion, and the type of precipitation that results is called orographic or relief precipitation.
The side of the highland which the wind strikes is called the windward side. The other side where the wind descends after crossing the highland is called the leeward side. This leeward side and beyond are said to be on the rain shadow of the highland, they receive less rainfall than the windward side.

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Frontal or Cyclonic precipitation
When two airmasses of different temperature collides, the warm moist lighter air tends to slide over the cooler denser air. The cold denser air forms a wedge under the warm light air. The uplift gives rise to cooling and condensation which eventually ends up in precipitation. The point in which these two airmasses meet is called front. Because this type of precipitation is normally associated with cyclones in the temperate region, it is called frontal or cyclonic precipitation. It is common in the mid-latitude low pressure belt, example in the British Isle and Western Europe and are also associated with linesqualls in West Africa.

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Reference
https://water.usgs.gov/edu/watercycleprecipitation.html
https://study.com/academy/lesson/the-water-cycle-precipitation-condensation-and-evaporation.html
http://www.physicalgeography.net/fundamentals/8f.html
http://www.physicalgeography.net/fundamentals/8e.html