This visualization tallies up all the lightning strikes detected by the Lightning Imaging Sensor (LIS) onboard the now defunct Tropical Rainfall Measuring Mission (TRMM) from April 1998 to January 2015—more than 16 years’ worth of lightning data. In orbit, LIS recorded the time of occurrence of a lightning event, measured the radiant energy, and estimated the location during both day and night conditions with high detection efficiency.
Lightning occurs more often over land than over the ocean because land absorbs sunlight and heats up faster than water. This means there is stronger convection and greater atmospheric instability, leading to the formation of more lightning-producing storms over land. The visualization starts out showing how the LIS sensor (green square) sweeps out an orbit path from approximately 35 degrees north to south latitude (blue), detecting lightning flashes as it passes overhead. As the sensor completes more orbits, a long-term count of the number of flashes observed at each location can be accumulated. Adjusting the total number of counts by the number of times the location has been observed gives the average flash rate, also known as a climatology (shown in the last frame of the visualization).