Precipitation Flashcards
What is precipitation?
It’s any form of water - liquid or solid- that falls from the sky. It includes rain, sleet, snow, hail and drizzle.
What is the most common form of precipitation?
Rain
How does rain form?
Rain occurs because air has been forced to rise. As air rises it cools and loses its ability to hold water.
What is the dew point?
When air reaches a point where it’s 100% saturated (it can’t hold any more water). It’s above this point that condensation occurs.
What is condensation?
It’s the process by which the water vapour held in the air is turned back into water droplets that falls as rain.
What are the 3 types of rain?
Convectional rain
Cyclonic (frontal) rain
Relief rain
Where does convectional rain occur?
Most commonly in areas where the ground is heated by the sun, it occurs during Irish summers sometimes but occurs all year around in hot regions near the equator such as tropics.
How is convectional rain formed?
The warm air rises because it’s less dense, as it rises it becomes cooler and condenses to form clouds that produce rain.
What is sometimes produced instead of convectional rain?
Thunder and lightning
How does cyclonic (frontal) rain occur?
When 2 air masses meet, causing a front
How is cyclonic rain formed?
The warm air cools and begins to condense after the front. As it rises further, condensation occurs.
What types of rainfall happen from frontal rain?
Moderate to heavy
What is the most common type of rain in Ireland?
Relief rain
How is relief rain formed?
Prevailing winds pick up moisture from the sea as they travel across it, making the air moist. When this moist air reaches the coast it’s forced to rise up over the coastal mountains and hills. This forces the air to cool and condense.
What happens after the clouds are formed in relief rain formation?
Once over the mountain, the air will usually drop down the other side, warming as it does so meaning it can hold more moisture. It also means there won’t be much rain on the far side of the mountain. This area is called rain shadow.
