If meteorologists had to pick their favorite punctuation mark,
many would probably choose a comma. That's because the cloud
pattern of a developing storm often takes on a comma-like shape
when viewed from space.  Here's a storm from a few weeks ago
that took on this characteristic comma. When you see this shape,
you can approximate where various parts of the storm are. First,
find the mass of clouds that forms the head of the comma. The
center of low pressure is usually just to the east of these
clouds. The storm's cold front typically extends south from the
low, near the back edge of the narrow band of clouds. And the
warm front usually extends east from the low, though warm fronts
can sometimes snake in convoluted ways.  As far as weather is
concerned, if you see a large comma cloud on a satellite image,
it almost always means that somebody's getting heavy rain or
snow and strong winds.