Hi Larry and all, When I looked at the sombrero picture I immediately thought of the Cosine Effect on solar intensity. Consider the length of the shadow of the cone on the brim. The longer the shadow the lower the intensity of the sun on the plane of the brim. By how much? By the cosine of the angle from the normal axis of the cone. To calculate this consider the sombrero as a reclining declining sundial with a gnomon perpendicular to the plane. The angle (theta) of the shadow from the perpendicular is the ATan of the length of the shadow divided by the height. The solar intensity is proportional to Cos theta that angle as the suns rays are spread over a larger area than the circular sombrero.
Every time our Mexican friend puts down his hat, he is showing us the relative solar intensity at that point. The sun bearing down directly causing no shadow is most intense with heating IR and burning UV rays. If the sun is at a lower angle, casting a longer shadow due to the time of day or latitude, the intensity is lower by the cosine of the shadow angle from the cone. He could draw rings on the brim to indicate the relative intensity and drop his hat on any surface to check the intensity. I have used this sundial science to advise a neighbour considering solar panels. Charts of intensity for various orientations, tilt and direction allowed him to determine the optimum and what to expect at different times of day and seasons of the year. Maybe he will save his money and go to Mexico for the winter instead of installing solar panels. Everything I need to know I learned from sundials. regards, Roger Bailey From: Larry Bohlayer Sent: Wednesday, August 17, 2016 3:44 PM To: [email protected] Subject: Sombrero as a sundial This sombrero is a reminder that we should all wear sundial hats to our next meetings. 20 points for the heaviest version. 50 for wearing it on the plane. I am sure that someone has perfected the idea into time readable fashion. A modified version with a "wakeup hole" to let the sunlight through to one's skin might actually work. This shortened url takes you to the Adobe Stock Photo website for the titled image of "Mexican man having siesta" by Rafael Ben-Ari. Stock#42495149. https://goo.gl/CFwZNy Larry Bohlayer 35.4N, 80.7W -------------------------------------------------------------------------------- --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial -------------------------------------------------------------------------------- No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.7752 / Virus Database: 4647/12827 - Release Date: 08/17/16
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