Online Encyclopedia of Western Signs and Ideograms Symbols.com

Symbol 24:24

2420a

24:24 · This sign is found among the Egyptian hieroglyphs, where originally it was a pictorial sign for a loaf of bread. It is also a common sign in modern Western ideography. It has been used in meteorology to signify dew and cumulus clouds. Turned upside down, 2420b, it could mean ring around the moon (also drawn 2420c).
    Both 2420a and 2420b are used in physics as signs for average light intensity.