Re: pinhole rainbow halos on pavement

Date view Thread view Subject view Author view Attachment view

From: pauld@exploratorium.edu
Date: Wed Jun 05 2002 - 11:07:29 PDT 

Message-Id: <200206051807.g55I7Pp20301@isaac.exploratorium.edu>
From: pauld@exploratorium.edu
Subject: Re: pinhole rainbow halos on pavement
Date: Wed, 5 Jun 2002 11:07:25 US/Pacific

Regan

Part 2

Sun Dogs are indeed fragments of solar halos.

When the ice crystals that make a halo fall and are just the right size they all
line up with their biggest flat faces parallel to the ground. Otherwise they
tumble in all orientations.

When they tumble they make a halo.

When they fall flat they concentrate the light from the entire halo in two extra
bright dots which are 22.5 degrees on either side of the sun called sun dogs or
parhelia.

They typically appear in North America about 80 times per year at sunset.

Paul D

are> as i was biking home i saw a rainbow around my shadow on the pavement
yesterday. i have
often taken this route before on similarly sunny days and never noticed this
rainbow. it
followed me for about three blocks and it was about one hand's width (fingers and
arm
extended) away from the center of the shadow of my head. is this related to the
sunhalos
or does this probably happen all the time?
>
> also, are sundogs just chunks of sun halos? i saw one on memorial day (interestingly,
i
saw it on I-80, near davis, where I have seen 2 before).
>
> thanks.
> -Regan
>
> ---------------------------------------------------------------------------
>
> To unsubscribe from pinhole, send an email to requests@exploratorium.edu
> with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT
> of the email.
>
> To subscribe to the digest and only get 1 combined message a day, send an
> email to requests@exploratorium.edu with the words 'subscribe digest
> pinhole' (without the quotes) in the SUBJECT of the email.
>
> Check out what your colleagues have written on Pinhole in the Pinhole
> archives at: http://saturn.exploratorium.edu/ti/alumni/pinhole.html
> ---------------------------------------------------------------------------
>
>
>

--------------------------------------------------
This message was sent using Exploratorium web mail
           http://www.exploratorium.edu/

Date view Thread view Subject view Author view Attachment view

This archive was generated by hypermail 2.1.3 : Mon Aug 05 2002 - 09:21:42 PDT