A flash of blue light sometimes seen briefly just above the sun as it is about to disappear below the horizon at sunset, or as it first appears at sunrise.
Origin
Late 19th century; earliest use found in The English Mechanic.
Definition of blue flash in US English:
blue flash
noun
A flash of blue light sometimes seen briefly just above the sun as it is about to disappear below the horizon at sunset, or as it first appears at sunrise.
Origin
Late 19th century; earliest use found in The English Mechanic.