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.