The Sphinx, a patch of snow believed to be the longest-lasting in the UK, has melted for the fourth consecutive year.

Iain Cameron has spent decades surveying the patch, hidden in one of the most isolated parts of Scotland’s Cairngorms.

Describing his work as “citizen science”, Iain and other experts document areas of snow across the country and share their findings with the Royal Meteorological Society.

The patch was thought to be a permanent fixture in the Scottish landscape – researchers attribute its recent melting to the effects of climate change.

A snow patch is a permanent or long-lasting area of snow, unlike seasonal snow cover that will melt during warm weather.

Video by Danielle Fleming and Morgan Spence