blue flash

noun

A very rare phenomenon observed in the morning or evening when the sun is crossing or immediately below the horizon, in which a momentary flash of blue light appears above the upper rim of the solar disk, caused by refraction of light in the atmosphere.

Ask AI about this wordChatGPTClaudePerplexityGoogle AIGrok

Meanings

nounblue flash (plural blue flashes)

plural blue flashes

  1. astronomyA very rare phenomenon observed in the morning or evening when the sun is crossing or immediately below the horizon, in which a momentary flash of blue light appears above the upper rim of the solar disk, caused by refraction of light in the atmosphere.
  2. nuclear physicsA phenomenon sometimes observed when a criticality accident occurs in nuclear materials, inducing a discharge of radiation into the environment.
Cite this entry
APA

blue flash. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/blue%20flash

MLA

“blue flash.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/blue%20flash. Accessed November 2, 2026.

Chicago

WatkinsX Dictionary, s.v. “blue flash,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/blue%20flash.

Source: blue flash on Wiktionary, CC BY-SA 4.0.