Rainfall & Clouds


Rain is the most common form of Precipitation. (Other forms are snow, hail, sleet etc) There are three main types of rainfall.

Relief Rain

Convectional Rain

Cyclonic (Frontal) Rain

Relief Rain

Relief rain occurs when moisture laden air is forced to rise over high ground. As the air rises it cools and the water vapour condenses to form rain, which then falls on the windward side. The other side of the high ground receives very little rain and is known as the Leeward side.

relief rainfall

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Convectional Rain

This type of rain occurs when warm air rises from warm land (i.e. During a very warm summers day) The rain takes the form of thundery showers, sometimes referred to as ‘cloud bursts’. The rain will be quite heavy. This type of rain happens sometimes in an Irish summer, but every afternoon in regions near the equator.


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Cyclonic (Frontal) Rain

Cyclonic Rain is also known as Frontal rain and this is very common in Ireland. This type of rain forms when a cold air mass and a warm air mass meet. The cold air from the north meets with the warm air from the south. The cold air forces the warm air up which then condenses and falls as rain.


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There are three main types of clouds.


These are very high in the sky, and they look like wispy brush strokes. These clouds won’t have any rain.



These clouds are like fluffy shapes, they occur at medium altitudes and they are not likely to bring rain, though some cumulus clouds may be dark and heavy with some rain.

Cumulus clouds


These clouds form a ‘Blanket’ over the sky and are generally low lying. Stratus clouds normally bring long periods of precipitation (Rain etc.)