SkyStef's weather page
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SkyStef's weather page |
Weather picture of the month April 2005
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| Picture taken at Steenokkerzeel on February 13 2005. |
| Crepuscular rays are
dark bluish streaks which radiate from the sun across the purple light.
These streaks are the shadows of clouds at or below the horizon, which
appear to diverge because of perspective effects.
Occasionally, the shadows may cross the sky, becoming visible again at the
antisolar point, thus called "anticrepuscular rays". Dust in the
air, inorganic salts, organic aerosols, small water droplets or the air
molecules self make these rays visible.
The name "crepuscular rays" is also used, though not universally, to denote shadowed bands cast by clouds on a layer of haze or mist at any time of the day. Not limited by the shadowing of clouds, they can also occur when sunlight crosses objects on the ground, like trees on a misty day.
The picture shows strong crepuscular rays due to the humid atmosphere with floating ice crystals. |
