Appearance in Satellite Data

In satellite images Cold Fronts appear as cyclonically curved synoptic scale cloud bands.

  • In the IR and VIS images the clouds vary between white and varying grey shades, according to their substructure and state of development.
  • In the WV images the cloud band is light grey with some white spots or stripes indicating embedded thicker clouds.
  • In RGB images the different types of clouds can be more easily separated, when compared to single channel images. In the Meteosat 8 0.6;0.8; 12.0 - combination high clouds appear bluish, thick multilayered clouds white or light grey and low clouds yellow. In METEOSAT 8 1.6; 0.8; 0.6 - combination ice clouds are cyan and water clouds grey (See Basics: Satellite Channels: Artificial and Combination Channels ).

Cold Fronts can be divided into two subgroups: Ana and Kata fronts. These types show a slightly different structure in satellite images.

  1. Ana Cold Front:
    • Generally smooth appearance
    • In VIS image, the brightest area is from the leading edge to the middle part of the cloud band, indicating lower water clouds
    • In IR and WV images the brightest area is from the rear edge to the middle part of the cloud band, indicating cold and high cloud tops, often with embedded CBs
  2. Kata Cold Front:
    • Structured appearance
    • In VIS image the brightest area is from the rear edge to the middle part of the cloud band, indicating lower water clouds
    • In IR and WV images the brightest area is from the leading edge to the middle part of the cloud band, indicating cold and high cloud tops, often with embedded CBs

It is not always easy to clearly separate Ana and Kata types. At the beginning of development the front is usually an Ana-type which becomes a Kata-type later. These two types can also exist within the same front.

The structure of Cold Fronts may also vary according to other features attached or embedded within it. Such conceptual models are Wave, Upper Wave, Front Intensification by Jet Crossing and Front Decay. A PVA maximum may also cause additional substructure. Kata Cold Fronts can sometimes look like a Split Front.

On the 19th of September 2005 at 12.00 UTC there was a Kata Cold Front stretching over Scotland and Ireland:

19 September 2005/12.00 UTC - Meteosat 8 IR 10.8 image
19 September 2005/12.00 UTC - Meteosat 8 WV 6.2 image
19 September 2005/12.00 UTC - Meteosat 8 VIS 0.8 image
19 September 2005/12.00 UTC - Meteosat 8 RGB image (0.6, 0.8 and 12.0)
19 September 2005/12.00 UTC - Meteosat 8 RGB image (1.6, 0.8 and 0.6)

On the 4th of October 2005 at 12.00 UTC there was an Ana Cold Front over the Atlantic. An Upper Wave is seen over the frontal cloud band south of Iceland.

04 October 2005/12.00 UTC - Meteosat 8 IR 10.8 image
04 October 2005/12.00 UTC - Meteosat 8 WV 6.2 image
04 October 2005/12.00 UTC - Meteosat 8 VIS 0.8 image
04 October 2005/12.00 UTC - Meteosat 8 RGB image (0.6, 0.8 and 12.0)
04 October 2005/12.00 UTC - Meteosat 8 RGB image (1.6, 0.8 and 0.6)