Question: @Ciarán , why does Ireland get so much rain?

Ciarán O'Brien answered on 19 Nov 2014:

We have the winds blowing in from the equator to thank for all our rain. Down at the equator the air is warmed by the sun a lot more than up here, which means more water evaporates into it. The air pressue is a bit higher down there as well, so it flows towards Ireland which usually has low air pressure. On its way, the warm air evaporates even more water from the oceans so there’s plenty of water in the air by the time it gets to Ireland.

When it hits Ireland, one of the first things it encounters is mountains: The warm air is coming from the south(ish), and the south of Ireland has a whole lot of mountains. The air is forced to flow up over the mountains, where things are colder. The air cools down and it can’t hold as much water any more, so a load of it condenses into liquid drops and they fall to the ground as rain. Ireland’s location about half-way between the equator (very warm) and the North Pole (very cold) means there’s always a lot of cold air coming down from the north to mix with the warmer air from the south, so you get a LOT of rain condensing out of the atmosphere here. On the other side of the planet, New Zealand is about half-way between the equator and the South Pole, so they get about as much rain as we do too!

Not all the water vapor falls as rain in the south of the country, there’s plenty left for the rest of the country too. If Ireland was a lot bigger, most of the rain would stop falling before the air had gotten to the other side of the country, but because we’re a small country we don’t get that break that other countries would. 🙂