Recent NASA satellite observations revealed lightning strikes occur more often over the land than the ocean, and are also more frequent closer to the equator.
A map created from the collected data counted the average annual flashes of lightning per square kilometer from 1995 to 2013, NASA's Earth Observatory reported. In the map, areas with the fewest lightning strikes are gray and purple, while those with the highest number are in pink.
The map is based on data collected by the Lightning Imaging Sensor (LIS) on NASA's Tropical Rainfall Measuring Mission satellite between 1998 and 2013 and the Optical Transient Detector (OTD) on the OrbView-1/Microlab satellite between 1995 and 2000.
The researchers said the higher frequency of lightning strikes seen on land because the Earth absorbs sunlight, causing it to heat up more quickly than the water. This phenomenon leads to stronger convection and higher atmospheric instability, which causes lightning storms.
The data also shed light on some regional trends, such as lightning strikes during the month of May in Brahmaputra Valley, India that occurred right before a monsoon that was characterized by dramatically fewer lightning events. On the other hand, locations in Central Africa and Northwestern South America proved to experience lightning strikes year-round. The highest concentration of lightning strikes occurred in the Democratic Republic of Congo and Lake Maracaibo in northwestern Venezuela.
The researchers noted the new map has not necessarily changed the common knowledge of global lightning patterns.
"The longer record allows us to more confidently identify some of these finer details. We can examine seasonality, and variability through the day and year-to-year," said NASA's Daniel Cecil, a member of the Global Hydrology and Climate Center's lightning team.
The findings were published in a recent edition of the journal Atmospheric Research.
