What Causes A Ring Around The Moon? - Spectrum News

NEW PODCAST EPISODETim Boyum talks with State Senator Michael Garrett on ICE, Bad Bunny COMMUNITY CALENDARAdd an event to our calendar WEATHER ALERTFull list of active watches and warnings CLOSINGS ALERTFull list of closings and delays Snty-tact What Causes a Ring Around the Moon? BY Meteorologist Matthew East North Carolina PUBLISHED 2:45 PM ET May. 09, 2019 SHARE

Ever seen a ring appear around the moon in the night sky? Ever wonder what that sometimes occurs?

Really, the meteorological setup for a ring to become visible around the moon is pretty simple. The key ingredient is having a layer of cirrus clouds streaming high overhead.

Cirrus clouds are high-level clouds, generally located at least 20,000' in the air. They are composed of ice crystals where super-cooled water droplets have frozen. 

When you have a bright moon in the night sky, the light from the moon is bent as it passes through the ice crystals in such a way that a visible ring is formed. This is a similar phenomena to light passing through a lens. 

Also, as a fun aside, often times when you see a ring around the moon, it can be an indication that a storm system will arrive within the next 24-48 hours. Reason being, cirrus clouds often precede incoming areas of low pressure. 

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