What my kids wanted to know

Almost every day, one or both of my sons, Colin and Robert, come up with questions that require a lot of thought and/or research. So I thought, hey, why should I do all the thinking?

This new site, then, is intended to present the questions to the cyberworld, and invite answers, theories, extrapolations, and comments from anyone who cares to respond.

Today's Question
When we flew to England, Colin noted that we flew above the clouds, and the clouds appear to form a pretty thick, uniform layer. So he wants to know why, if this blanket of cloud is always up there, do we see clear blue skies down here?

I wasn't satisfied with the two "if it's cloudy above it's cloudy below" answers to the previous post, since I too have observed the unbroken layer of cloud - every single time I've flown to or from the UK, which I've done fairly often.

So I went looking - so much for letting other people do the work for me!

From what I understand (and try to remember I'm an English teacher, not a scientist), commercial aircraft fly above the tropopause, which is the region between the troposphere and the stratosphere.

Most weather, and therefore visible cloud formation, occurs in the troposphere. From below, the tropopause is only visible when weather from below hits it.

From above, however, the tropopause looks like an unbroken blanket of cloud.

The physics prof's answer, then, probably means that the blue sky we see is light refracting from the solid tropopause.

Corrections, emendations, and additional info always welcome!

Today Colin wants to know why people have different skin colours.

Today's question is what do they use for snow in movies such as The Chronicles of Narnia?

Thanks for all the response so far! Colin is very excited. Robert is still pretty much oblivious, but his time will come.

Colin is reading the second Harry Potter book and wants to know if people really do have a sixth sense, and if so, does danger always happen if they get a feeling it will?