Di­vine dig­its on high

Cape Breton Post - - WEATHER - Cindy Day is SaltWire Net­work’s Chief Me­te­o­rol­o­gist. CINDY DAY

The other day I re­ceived an email from Heather Crocker. She was at her cot­tage in Mala­gash, N.S., when she looked up and saw what she de­scribed as rays com­ing up from the wa­ter. She was fa­mil­iar with the rays that streak down from the sun, but this was new to her. She wanted to know what caused the up­side-down ef­fect.

Well Heather, both are ex­am­ples of cre­pus­cu­lar rays.

The beams of sun­light that ap­pear to burst from be­hind a cu­mu­lus cloud or shine down through a hole in the clouds are sur­pris­ingly the less com­mon of the two.

When the sun is high in the sky, the shafts of light ra­di­ate down to­wards Earth. They ap­pear when the path of sun­light is made vis­i­ble by wa­ter droplets in the air – too scarce to ap­pear as clouds but plen­ti­ful enough to no­tice­ably scat­ter the light.

Cre­pus­cu­lar rays beam­ing up from the hori­zon are more com­mon. They ap­pear as pil­lars of sun­light, all con­verg­ing at a sin­gle point, stream­ing up­ward. They’re most com­mon dur­ing twi­light hours when the con­trasts be­tween light and dark are the most ob­vi­ous and that’s where they get their name.

If you hap­pen to no­tice the cre­pus­cu­lar rays, turn around so your back is fac­ing the sun. There, ahead of you, should be the an­ti­cre­pus­cu­lar rays. These rays also con­verge to­ward a point but di­rectly op­po­site the sun. That point is known as the an­ti­so­lar point.

While these shafts of light ap­pear to be con­verg­ing to­ward the sun or the source of light, the rays are in fact al­most par­al­lel shafts of sun­light. The ap­par­ent con­ver­gence is a per­spec­tive ef­fect.

The word cre­pus­cu­lar comes from the Latin “cre­pus­cu­lum,” mean­ing twi­light. But I pre­fer their com­mon name: God’s Fin­gers.

While ad­mir­ing the sun­set at her cot­tage in Mala­gash, N.S., Heather Crocker spot­ted these sub­tle shafts of light com­ing up from the wa­ter.

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