Question: ben,in a picture of the earth the blue bit is the sea,the green bit is the land' so where is the sky?

Ben Still answered on 15 Nov 2011:

The atmosphere is pretty transparent to visible light which is why we don’t see it on pictures of the Earth, you will see clouds in the pictures though as they are not. The transparency of the atmosphere is a good thing as it lets light hit the ground where some is absorbed by the plants, sea and ground. The atmosphere is however not too transparent to infra-red radiation, which is just light of a lower wave length. Infra-red is emitted by the ground and sea and trapped by the atmosphere – this way heating the Earth. If you looked at the Earth from above in infra-red instead of visible light it would be much harder to see the ground and sea.