Snow rollers: What are they and how do they form?

As you've been showing us all week, there's loads of things you can make with snow - snowmen, snow angels, and even igloos.

But did you know nature can make cool things with the snow all on its own?

People in Orkney (an island off Scotland) have seen some wintry wonders called snow rollers this week.

They're a rare phenomenon where the wind makes its own snowballs.

Once one has been formed, strong winds keep it rolling along the ground, meaning it gets bigger as it moves and sometimes leaves tracks behind it.

They're rare because the conditions they need to form are very specific.

Have you ever seen snow rollers? Let us know in the comments below.

Obviously need snow, but not necessarily loads.

They are so rare because in order for them to form everything, including the amount of snow, has to be just right.

The Royal Meteorological Society say the following conditions are needed for snow rollers to happen:

If the wind is too strong, or too weak, or the snow is too tightly packed, snow rollers will not form.

The resulting snowballs look a bit like a hay bale, a doughnut or a Swiss roll, and can be hollow inside.