Day 9: Snow Covered England

Posted by pmarsh on 9 Jan 2010 | Comments Off

Well, as an answer to yesterday’s post, areas in an around Tampa, FL received light freezing rain and periods of sleet this morning.  Nothing major, just enough to say it happened.

Tonight will have a bit of an international component.  The first weather chart is a visible satellite image taken earlier this week.  It shows an almost entirely snow covered United Kingdom (the white areas surrounded by green and blues), something I’m not sure has ever happened during the modern meteorological observing era.  Even though the United Kingdom is located at a relatively high latitude, the waters surrounding the area are relatively warm as a result of the Gulf Stream Current.  As such, snow in a majority of the United Kingdom is uncommon – particularly amounts of this magnitude.

Not everything that is white on the satellite image is snow cover.  Clouds, which also show up as white in visible satellite imagery are also present (an example is the north-south band located between England and Ireland over the water…another area of clouds is located in the bottom-right portion of the image).  While it can be difficult to distinguish between snow and clouds in the image, the easiest way to distinguish between them is to examine the apparent depth of the feature in question.  Snow cover has a 2-D (or flat) look to it, whereas clouds have a 3-D look to them.

The United Kingdom is not the only place in the Northern Hemisphere experiencing above normal snowfall this winter.  As previous posts have mentioned, the United States is currently in the midst of its own winter blast.  The second image is also of snow cover, but over a much larger area (almost a factor of 10) than the United Kingdom.  For the most part, there are no clouds in the image below and all white areas can be considered snow cover.  Of note in this image (in addition to the sheer size of the snow cover) is how easily lakes and rivers can be identified.  The “vein” looking features in Iowa and southern Minnesota are places where snow has not accumulated, almost always the result of snow falling into lakes and rivers and melting in the water.