Petrichor: Why does it smell after it rains?

The UK has been enjoying the hot weather recently, but after sunny spells the rain has hit.

Thunderstorms have brought rain and flooding to parts of the UK this week.

But have you ever noticed the smell of rain after a long period of dry weather? It can sometimes smell warm, earthy and a bit like concrete? Well that smell has a name - petrichor.

Find out what petrichor is and why rain causes the smell below!

What is the word for the smell of rain?

Petrichor is the word for the smell of rain. It comes from the Greek words, petros meaning "stone" and ichor meaning "the fluid that flows in the veins of the gods".

The term was first used by two researchers in 1964 who worked at an Australian science agency.

In their research they found that when rocks had been exposed to warm, dry conditions they released a yellow coloured oil that had been trapped in the rocks and soil. This substance was partially behind the smell.

Why does it smell after the rain?

Along side the oil from rocks, the smell also comes from bacteria which live in the soil.

When the weather is dry and warm, plants in the ground release oils into the soil to stop other seeds from germinating - which is when a seed begins to develop into a new young plants.

This mix of bacteria and oils is called geosmin, and when the rain hits the ground, it gets caught in the rain drops and as the drops burst they release geosmin into the air.

So now you know it's this mix of oils and bacteria combined with the rain that makes that smell we love.

Next time there's rain after a sunny day you can confuse and impress you family and friends by saying, "Mmmmm, petrichor!".