How It Works

Britain’s big freeze – 7 January 2010

Snowy Britain NASA

Image courtesy of NASA

The Moderate-Resolution Imaging Spectroradiometer (or MODIS) on board NASA’s Terra satellite captured this incredibly chilling image of Great Britain on 7 January as most areas experienced freezing temperatures of -10C on the coldest night of the winter so far. Isolated areas were even subjected to lows of -22C in the Scottish Highlands.

Snowfall followed by freezing temperatures left areas dangerously icy, resulting in widespread chaos on the roads. Schools across the nation were closed and many businesses sent staff home. The emergency services, including roadside assistance, were inundated with incidents.

One possible reason for the severely cold conditions across the Northern Hemisphere this last month is an extreme negative phase of Arctic Oscillation (AO). AO refers to a state of seesawing atmospheric pressure over the Arctic. The negative phase of AO causes high pressure over the polar region and low pressure at mid-latitudes.

MODIS images the entire Earth every one to two days. The grey areas against the white land surface on the map are actually the cities of Manchester, Birmingham and London.