Cloud Shadow imaged by Henry Kunz from the Diemtigtal in the Bernese Oberland, Switzerland. ©Henry Kunz, shown with permission.

We often see a cloud apparently casting a shadow upwards. And yet the sun always, or nearly always, shines downwards. Shadows therefore cannot beam up.

The shadow is being cast on a nearer and lower layer of haze and we see it as through the back of a cinema screen. One clue is that the shadow appears larger than the cloud -- It is closer to us.