February 16, 2012
Photographer: Jim Grant
Summary Author: Dave Lynch; Jim Grant; Jim Foster
This “split screen” sunset was snapped at Ponto Beach near Carlsbad in southern California on January 24, 2012. The scarlet-colored cirrus clouds on the right half of the photo could, under some circumstances, result from the fact that they're higher in the sky and are thus still picking up some of the Sun’s lingering rays. However, all the clouds look pretty much the same altitude here. It seems the only difference is that half the picture is conspicuously redder than the other half, but what could cause this? The reason has to do with shadowing. As illustrated in the diagram to the left, direct sunlight (reddened by increased path length) shines on some of the clouds but the shadow of the large cloud (white oval) prevents direct sunlight from reaching other clouds. Only blue skylight reaches the smaller clouds within the shadow, so they appear somewhat blue or gray. In essence, the bigger cloud casts a very large, dark crepuscular ray. Keep your eyes peeled to the sky – you never know what you might see.
Photo Details: Camera Maker: NIKON CORPORATION; Camera Model: NIKON D80; Focal Length: 18mm (35mm equivalent: 27mm); Aperture: f/3.5; Exposure Time: 0.040 s (1/25); ISO equiv: 320; Exposure Bias: none; Metering Mode: Matrix; Exposure: shutter priority (semi-auto); White Balance: Manual; Light Source: Flash; Flash Fired: No; Orientation: Normal; Color Space: sRGB.