A line of showers and storms passed through the eastern half of the country on Thursday, producing interesting cloud structures known as shelf clouds.
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"A shelf cloud is the boundary between a downdraft and updraft of a thunderstorm or line of thunderstorms," says weather.com senior meteorologist Jon Erdman.
"Rain-chilled air descends in a thunderstorm, then spreads laterally when reaching Earth's surface. Warmer, more moist air is lifted at the leading edge, or gust front, of this rain-cooled air. When this warm, moist air condenses, you see the shelf cloud."
(MORE: Shelf Clouds - Not Tornadoes, But Still Scary and Ominous)
"As the shelf cloud passes, you feel an abrupt wind shift in both direction and speed, followed within minutes by heavy rain or hail. Wind gusts once the shelf cloud has passed may be quite strong, causing downed trees, tree limbs and power outages."
Check out the latest pictures of the shelf clouds from around social media.