Diffraction and Other Phenomena Corona around the Moon Dr. Christopher M. Godfrey Colors appear when particles have uniform size University of North Carolina at Asheville Image ©2004 Mount Washington Observatory ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Iridescence – Diffraction Glory Different sized droplets distort a corona Pastel colors appear in high, thin clouds Image © Shannon Story ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Glory Glory Image © Jonathan Lansey Image © C. Godfrey ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 1 Glory Brocken Spectre and Glory Image © Ann Bowker Image © C. Godfrey ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Other Optical Phenomena Crepuscular Rays Dust, water droplets, and haze all scatter light from the sun after passing through breaks in the clouds Rays are parallel Perspective makes rays appear to diverge Rocket Trails Image © Robert Koch ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Crepuscular Rays Crepuscular Rays Image © C. Godfrey Image © C. Godfrey ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 2 Crepuscular Rays Anticrepuscular Rays Convergent at the antisolar point* Extension of crepuscular rays East West Note scattering of light Antisolar point above the cloud *Don’t confuse the antisolar point with the anthelic point, Image © C. Godfrey which lies 180° in azimuth away from the Sun ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Anticrepuscular Rays Anticrepuscular Rays Image © C. Godfrey Image © C. Godfrey ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 Sun Pillar: A reflection phenomenon Heiligenschein ATMS 455: Physical Meteorology – Spring 2021 ATMS 455: Physical Meteorology – Spring 2021 3 Heiligenschein ATMS 455: Physical Meteorology – Spring 2021 4.