There are various cloud patterns which are readily observed in satellite imagery which meteorologists use to forecast the weather. As the cold air flows across the relatively warmer surface it will trigger the warmer air near the ground to rise. What appears as a towering cumulus cloud from the ground, often associated with heavy showers and sunny spells, shapes into a polygonal pattern of regular convective cloud elements.The convection cells are growing as the temperature difference (gradient) between the surface and the upper level air increases. Small convection cells form a so-called closed cells in a mainly covered cloud field, while bigger convective cells form open cells with mostly cloud-free areas with clouds produced around the edges of the cell.

The satellite image of November 8, shows a lobe of cold air dropping down across the British Isles and central Europe, with open and closed cells. If you compare it with the upper-level air temperature chart below, you will easily see where the coldest air was. However, this downflow of cold arctic air marked the first spell of winter of the 2001-02 season over the British Isles.

For more satellite imagery click here.
For more upper level charts click here.