The wind blows around the sand so no one grain of sand stays in the same place forever. The winds molds the sand dunes for a very short time
I think this question is meant to be placed in the Geometry category. :)
Fish reproduce to quickly
The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Normal warming is mostly caused by natural gases.
