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Most of the ice you see in photos of the Arctic is sea ice. Sea ice is created when the Arctic Ocean freezes. In this photo you can see a pressure ridge, created when two ice floes push up against each other.

There are examples of land ice in the Arctic, such as the Greenland ice sheet and glaciers in places such as Svalbard.

People often think that the Arctic is all white, but there are many shades of blue, pink and gold as the sun illuminates the ice.

It is often very hard to tell whether it is night or day in the Arctic. At high latitudes (i.e. as you get closer to the poles), the sun moves in a low arc. This means 24 hour darkness in winter and 24 hour sunlight in summer.

The dark gap between two sections of ice is called a lead (pronounced leed). These can be very dangerous and difficult for the explorers, but they also play a role in how fast the ice melts. The sun can heat the exposed water, which can then start to melt the underside of the surrounding ice.

This layer of ice has been pushed up on top of another by ocean currents and wind. You can see how this sea ice is made up of different layers as well as a layer of snow on top.

Although it is 'just' frozen sea, travelling across the Arctic ice is difficult, ice rubble piles up in pressure ridges, and leads can appear.

The snow and ice conditions changed for the explorer teams on a daily basis. This may look beautiful in the classroom, but it can be difficult to walk over. The snow drifts are called sastrugi and the lumps are called rubble.

Solar effects happen everywhere, but they are more common when there are ice particles in the atmosphere and when there's a clear sky. After you come back from the Arctic you start to notice more effects in the sky at home. This sun dog (or parhelion) and the sun column is caused by light from the sun being refracted through ice crystals.

Sun pillars or columns are a kind of optical phenomenon which is formed by the reflection of sunlight by ice crystals that are present in the Earth's atmosphere. Sun pillars are more likely when the sun is just below the horizon.