Images supplied by environmentalists and aerial photographers, meteorologists and satellite agencies.
The destructive force of an avalanche can be immense; from roads and railways can be blocked, power supplies can be cut off, or evening causing death. Avalanche defences try to reduce the hazard of these by techniques such as lessening the amount of snow in a snow pack to cause an avalanche and avalanche barriers.
A collection of stunning supercell and lightening photos by Roger Hill. Supercell thunderstorms are severe long-lived storms within which the wind speed and direction changes with height. Roger has captured these incredible forces of nature over a number of years across the US.
From earth and from space, the Aurora Borealis is a breath-taking sight. Visible in the night sky at high latitudes, they occur when charged and energetic particles from the Sun (the solar wind) are drawn by Earth's magnetic field to the polar regions. Hundreds of kilometres up, they collide with gas molecules and atoms, causing them to emit light. Explore this collection of Northern Light photos here.