sub·​storm | \ ˈsəb-ˌstȯrm How to pronounce substorm (audio) \

Definition of substorm

: a disturbance in the magnetosphere that manifests as increased activity in the aurora (see aurora sense 3) and that is caused by an influx of high-energy particles from the sun (as from a solar flare) Even when the sun is being well behaved, parcels of plasma shoot sporadically toward Earth's dark side, prompting a bright aurora and intensifying radiation belts. These events, called substorms, last only a few hours, but they occur several hundred times a year and are quite capable of disrupting satellites …— Tim Beardsley

Examples of substorm in a Sentence

Recent Examples on the Web

Ninety seconds after the satellites sensed the substorm starting, ground observatories witnessed a Northern Lights display suddenly brighten and dance. Brandon Keim, WIRED, "Scientists Discover What Makes Northern Lights Dance," 24 July 2008

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'substorm.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of substorm

1961, in the meaning defined above

Keep scrolling for more

Learn More about substorm

Statistics for substorm

Look-up Popularity

Time Traveler for substorm

The first known use of substorm was in 1961

See more words from the same year

Comments on substorm

What made you want to look up substorm? Please tell us where you read or heard it (including the quote, if possible).


a wrong name or inappropriate designation

Get Word of the Day daily email!

Test Your Vocabulary

Summer 2019 Words of the Day Quiz

  • a-bowl-of-peach-sorbet-with-cut-peaches-next-to-it
  • Which is a synonym of desideratum?
True or False

Test your knowledge - and maybe learn something along the way.


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!