The sun always, or nearly always* shines downwards and therefore shadows nearly always point down.
Yet appearances can deceive. These shadows, like many, look as though they are projecting upwards onto a higher cloud layer - A trick of perspective. There is thin cloud and stratus haze below the towering cumulus. The cumulus shadow is cast down onto this lower layer. Viewed from some positions on the ground the shadow tip appears to project above the cumulus tops.
| * |
When the sun is almost below the horizon or even just below it, atmospheric refraction can curve its rays around the earth and make them slant very slightly (no more than a fraction of a degree) upwards. |
|
