World Map of Lightning Activity

Ian writes "NewScientist.com is >reporting that you can now see the lightning activity on the entire planet Earth at one time. The article states, "The NASA map also shows that lightning very rarely occurs at sea and is almost never seen at the Earth's poles." Anyone care to speculate on why that is?"

Comments

My Estimation

[Nater]

My estimation is that the extremely low lightning at sea is caused by a general lack of geographic anomalies to disturb airflow.

You'll notice in the map a wide swath of sea to the west of South America which follows the equator and then curves south following the coast. This is approximately the path of the Humbolt and equatorial currents in the South Pacific. Winds and sea currents have a strong influence on each other, and so we may presume that the winds over these strong ocean currents are less turbulent than those over the Polynesians or the Carribean islands. This is consistent with the hypothesis that a lack of turbulence is the cause of low lightning occurrence at sea.

At the poles, the temperature is very low. I'm not sure of the mechanics involved, but I do know that regions with surfaces heated by the sun experience more lightning in general, so we could reasonably presume the opposite about regions of cold surfaces, explaining the lack of lightning at the poles.