Why is the sky blue during the day and dark at night?

Two nice physics videos that explain a part of the question above.

Walter Levin does two magnificient demonstrations: in the first he shows why the period of a pendulum is independent of amplitude and mass (this part is cool!). In the second demonstration, he explains beautifully how Rayleigh and Mie scattering conspire to make the sky blue, clouds white, and sunsets red.

The MinutePhysics channel on YouTube also has a lot of snappy videos. Here is one that tries to explain why the sky is dark at night.

Feynman Lectures

I found a this link via Simoleon Sense. It is really a fabulous resource, and I highly recommend it, even if your interest in physics is only marginal.

From the blog:

Apparently, Bill Gates has purchased the rights (to many of the Feynman lectures) and posted them for free on his Microsoft Research Labs “Project Tuva”. I can’t recommend these enough, Feynman had the ability of teaching science in a simple, insightful, and eloquent manner.

Often all it taken to enliven a dull subject is a spectacular teacher, and few can doubt Feynman's charisma. What Warren Buffet is to investing, Feynman is to general physics. They serve their specialties with a hearty dose of common-sense and humor.

The only problem with these lectures is that it requires SilverLight!