sub·​storm ˈsəb-ˌstȯrm How to pronounce substorm (audio)
: 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, 24 July 2008

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'substorm.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1961, in the meaning defined above

Time Traveler
The first known use of substorm was in 1961

Dictionary Entries Near substorm

Cite this Entry

“Substorm.” Dictionary, Merriam-Webster, Accessed 18 Jun. 2024.

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