Rainfall

• Rainfall is just one form of precipitation.
• Precipitation occurs when warm moist air rises or is forced to rise.
• Water vapor in the air parcel cools and condenses to form clouds.
• This is because temperature falls with increase in altitude.
• When condensation occurs it produces minute droplets of less than 0.05mm in diameter.
• When these droplets join together and grow to fall of their own weight it is called rain.
• There are other forms of precipitation besides rain such as sleet, hail, dew, hoar frost, fog and rime and snow.

Types of rain

• There are various types of rain depeding on how the air rises/ is forced to rise these are:

Other types of precipitation

1. Sleet

Sleet falling image by Pixshark

• A mixture of snow and rain.
• Usually formed by snow melting as it falls.

2. Hail

A hailstorm. Image via Riverfronttimes.

• A solid form of precipitation.
• It consists of balls of irregular lumps of ice falling from the sky each of which is called a hailstone.
• When large chunks of ice falling from the sky it is referred to as a hailstorm.

3. Dew

Dew in the morning. Image by UK Met Office

• Dew is the small droplets of water that appear on objects such as leaves or grass in the morning or evening due to processes of condensation.
• Dew forms when the temperature of a surface cools down to a temperature that is cooler than the dew point of the air next to it.
• The temperature at which droplets form is called the dew point.

4. Hoar Frost

Hoar Frost. Image via DevianArt.

• Frost is the coating or deposit of ice that may form in humid air in cold conditions, usually overnight.
• Is common in places like Nyanga, Marondera and some parts of Harare in winter.

5. Fog/Mist

Fog. Image via MediaWiki.

• It is a visible mass consisting of cloud water droplets or ice crystals suspended in the air at or near the Earth’s surface.
• Fog can be considered a type of low-lying cloud, and is heavily influenced by nearby bodies of water, topography, wind conditions, and even human activities.
• Fog reduces visibility to less than 1 km while in a mist visibility is reduced to between 1 and 2 km.

6. Rime

Rime. Image by MediaWiki

• is a white ice that forms when the water droplets in fog freeze to the outer surfaces of objects.
• Often seen on trees.

7. Snow

Snow. Image by Crossvillenews.

• is precipitation in the form of flakes of ice particles that fall from the clouds.
• Snow does not occur in Zimbabwe although it is common in countries like the UK during winter.

8. Drizzle

Drizzle. Image by Gothamgirlchronicles.

• Very fine rain.
• Usually falls from layers of cloud that have very limited vertical development e.g stratus clouds.

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