At the fall meeting of the American Geophysical Union last December, investigators reported that lightning is more common and widespread than previously believed and that it plays an important role in global climate. The unlikely source of much of the recent information comes from data sent back to earth by a small satellite designed to detect clandestine nuclear weapons tests. The satellite makes several passes each day over the lightning prone equatorial tropics. The measurements are sufficiently detailed that the researchers can pick out signals from the separate processes that culminate in an atmospheric discharge. The combined data may help meteorologists to identify radio signatures of storm systems that spawn tornadoes or rain down damaging hail.
Lightning often occurs within clouds, especially over the oceans.
These lightning discharges are an indication of the way heat is being transported around the earth by the atmosphere. A portion of the sun's energy reaching Earth is captured and redistributed globally through latent heat carried in water vapor. The heat is released when the water vapor condenses and falls as rain. Storms with lightning tend to be more intense and release more heat. Tracking such systems may indicate where large amounts of heat are being released.