Tag Archives: supercooled liquid clouds

Distinguishing clouds over ice surfaces

The MODIS channel 3-6-7 blend available on Worldview is very effective at distinguishing clouds over ice surfaces. In this Worldview scene near Antarctica (1st Feb 2013; 73S, 103W), in the MODIS 3-6-7 channel blend (image below), one can see open ocean (black), surface sea/land ice (red), and clouds overlying them both (whiter hues). In visible imagery (image at bottom), it is often difficult to distinguish between clouds and sea ice. It is interesting that some of these clouds are so optically thin that one can see the outline of the ice edge through them.

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Clouds looking for a model to host them

Worldview shows the Southern Ocean clouds that climate models struggle and strive to represent. Almost exclusively found poleward of the storm track, these extensive layer clouds are constructed from multiple and single layers, frequently decoupled from the surface. Surprisingly, sometimes convection seems to be present, making one wonder whether the layers may sometimes be fed by cumulus detrainment. Much of their optical thickness appears to be attributable to supercooled liquid water.

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In Worldview’s 3-6-7 channel blend (primarily indicating microphysical differences), the convective elements can be seen in orange/red, penetrating the yellow/whiter stratiform layers:

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