Abstract
Although the intensity and frequency of lightning and rainfall are
higher over the continents and during the daytime, the place with the
most lightning in the world is Lake Maracaibo, a tropical lake in
Venezuela with nighttime thunderstorms. Lake Maracaibo is a very large
and warm lake surrounded by Andes mountains, the perfect scenario for
convergent windflow (mountain–valley, lake, and sea breezes) over the
lake nearly year-round, contributing to nocturnal thunderstorm
development over 290 days per year on average. Several other tropical
lakes with similar physical features (e.g., large area and elevated
topography nearby), also exhibit deep nocturnal convection driven by
locally forced convergent flow. We use the 16 years of precipitation and
lightning activity observed by the Tropical Rainfall Measuring Mission
(TRMM) to study the relationship between the physical characteristics
(size, shape, local topography and water temperature) of tropical lakes
and the precipitation and lightning activity of their thunderstorms. We
found that nearby elevated topography and the size of the lake are
important for deepening the convection and for increasing the electrical
activity, having local driven breeze circulations as one of the
consequences. Our results also suggest a nearly linear relationship
between the lake area and lightning activity over the lakes. Each water
body presented different characteristics, however, on average they show
more intense thunderstorms in the summer months and nighttime period
(e.g., higher reflectivity values deeper in the cloud, lower minimum
brightness temperature, higher convective precipitation volume).