Tuesday, 7 February, 2012

Why is the sky blue? Half Dome (in California’s Yosemite National Park) under a bright blue sky. To understand why the sky is blue, we need to understand a little about light. Light is a form of electromagnetic energy, which can propagate through empty space. We describe this energy by wavelength – the distance between [...]

The colors of the sunset result from a phenomenon called scattering, says Steven Ackerman, professor of meteorology at UW-Madison. Molecules and small particles in the atmosphere change the direction of light rays, causing them to scatter. Scattering affects the color of light coming from the sky, but the details are determined by the wavelength of [...]

Scott Bachmeier, a research meteorologist at the Cooperative Institute for Meteorological Satellite Studies at UW-Madison, says that particles in the air scatter light. In the day, the particles scatter more violet and blue light, but our eyes are more sensitive to blue light — that’s why the sky appears blue. Thunderstorms, which can be the [...]

Clouds are made of uncountable tiny particles, either water droplets or ice crystals, or a mixture of the two, says Grant Petty, a professor of atmospheric and oceanic sciences at the University of Wisconsin-Madison. “The water droplets are usually about 10-20 micrometers across, or about one-twentieth of the diameter of the period at the end [...]