Clouds appear white to us because they reflect light. Since visible imagery depends on available light, it can only be detected during the day. Atmospheric water vapor is an important factor in determining local weather and global climate. On these maps, white and light grey areas contain the most water vapor, while the dark areas are the driest. Very bright areas are storms and hurricanes.
Big spirals show large-scale circulation patterns in earth's atmosphere.
Radar uses radio waves to measure the time it takes to send and receive electromagnetic pulses. Radar images are useful for locating precipitation. A radar sends a pulse of energy into the atmosphere and if any precipitation is intercepted by the energy, part of the energy is scattered back to the radar. However, ALL sets use color-coding to show the relative thickness of cloud cover. Click here to check your answer.