Khan Academy
Khan Academy: What Is Urban Growth?
How were cities formed? This article explains the formation of cities starting from the neolithic revolution to current times. It addresses such topics as urbanization, suburban sprawl, and urban growth models.
University Corporation for Atmospheric Research
Ucar: Visualizing Weather and Climate
With visualizations, we can see the entire planet from all angles at once. We can see the invisible - such as water vapor in the atmosphere and the way air flows around the world.