It's always remained a mystery as to why lightning strikes are fewer over oceans than land, but we may just finally have the answer.

Scientists have discovered that less lightning occurs over tropical oceans, after analysing differences in atmospheric conditions over a five-year period in the oceans bordering Africa.

Lightning occurs when updrafts in clouds form ice crystals that bump into one another, producing an electrical charge.

The energy is then discharged as lightning strikes when one part of the cloud becomes positively charged, whilst the other becomes negatively charged.

Over the ocean however, when water evaporates, the salt water bonds with aerosols to form water droplets. These droplets tend to be larger and heavier than those that form over land, due to the presence of the salt.

Because of this, the droplets fall out quicker and don’t get a chance to rise, cool and form ice crystals, so fewer lightning strikes are discharged as a consequence.

This finding could help improve the accuracy of weather models, but also could lead onto a geoengineering concept, whereby storm clouds are seeded with salt in order to reduce their severity.