Step 2: Select Appropriate Channels or Channel Derivatives

Here are the solar, water vapor, and longwave infrared groups of MSG channels for this daytime dust storm over northern Africa.

Chart of the MSG visible, water vapor, and longwave IR channels that can be used for creating the dust RGB.

Which group best depicts the boundary of the advancing dust front (the area within the ovals in the 0.6-µm VIS and 10.6-µm IR images)? (Choose the best answer.)

The correct answer is C.

The longwave channels (8.7-µm infrared and longer) do the best job since dust contrasts with the thermal background, highlighting the front distinctly.

The solar channels do not have this capability since the reflective dust blends in against the bright desert background.

The water vapor channels cannot detect dust and land features since they do not see down to the surface where the dust often resides.