On 23 November 2013 at 06 UTC, the Polarstern is located at 53.1°S and 12.6°E (the yellow star on the imagery). We’ll identify current conditions by reviewing satellite imagery. Click the tabs to view the Airmass RGB and enhanced IR animations and the daytime Natural Color RGB image. Then answer the question below.
Given the cloud structures over the South Atlantic Ocean, what is the dominant weather system in the area west of the Polarstern?
A cold front is indicated on the satellite imagery. Cold fronts are depicted by cloud bands that form an "inverted comma" on satellite imagery in the Southern Hemisphere (a "comma" in the Northern Hemisphere). These cloud bands spiral into a vortex to the south of the frontal cloud band. A warm front can also be seen emanating from the vortex.
A surface front is often best depicted in visible imagery or, as in this case, the daytime Natural Color RGB where the cloud formations and positioning of the low pressure vortex are clearly visible. Notice the speckled cloud patterns south and west of the cold front that are typical within the colder and somewhat unstable airmass.
In contrast, IR imagery can be useful for identifying fronts at night. However, cloud features are not as easily identifiable due to the courser resolution of the imagery when compared to visible channels, and the more subtle temperature contrast between low clouds and ocean surface.
The Airmass RGB combines water vapour, ozone, and infrared channels to differentiate between cold and warm airmasses. While this can be useful for identifying the general location of surface fronts, detailed low-level cloud features associated directly with fronts are more difficult to see. That’s because the main purpose of the product is to highlight contrasting thermal and moisture properties of differing airmasses.