To celebrate Science Week, the RTÉ Weather team are sharing some fun facts about - you guessed it - the weather! Today, Michelle Dillon explains the relationship between air pressure and rain.
Air moves from areas of high pressure to areas of low pressure. This is how wind happens and how we determine the direction of the wind.
When air moves quickly from an area of high pressure to an area of low pressure, it can make a pop - like when a balloon bursts or in our ears when we land or take off in a plane or drive quickly down a mountain. That's the air pressure changing rapidly.
When air rises in an area of low pressure it starts to cool. That cooler air can carry less water vapour - that's water in its gas form - than warmer air, it condenses in to cloud and when the cloud gets full, it spills out in rain.
So that is why in and around areas of low pressure we have rainy weather with showers.
What goes up, must come down. Sometimes with a heavy shower, we feel the descending air coming ahead of the rain, that's called a downdraught.
If you're out and about on a showery day, watch out for that cool wind that picks up out of nowhere. That's the downdraught telling you a heavy shower, sometimes with hailstones is on its way.
