Question: What causes it to rain so much in The Highlands??

Daniel Parsons answered on 12 Nov 2014:

Hi there,
It rains so much in the Highlands in general because of something called orographic rainfall or orographic precipitation. This is produced because air masses are pushed by wind are forced up the side of hills and mountains. The lifting air cools and forms condensation – a bit like how the window in your house or car gets steamy when its cold outside! The condensation forms clouds that then produce rain when the droplets get big enough to fall.
In the UK and the Scottish Highlands this is enhanced as the air masses are coming from an ocean source (the Atlantic), which means the masses of air already have lots of moisture in them. It also explains why Aberdeen gets less rain than Fort William, because by the time the air masses get to Aberdeen lots of the rain has fallen out of the clouds and there is not that much left!