Brown seaweed is to blame for some of those cloudy days at the seaside, scientists believe. Stress among the plants can alter weather patterns, according to researchers at the Scottish Association for Marine Science and the University of Manchester.

On an overcast day kelp are comfortable when the tide goes out, as they stay damp until it comes in again. But on a bright day they dry, releasing iodide. The iodide rises, causing clouds to form overhead, sheltering the kelp from the unwelcome sunshine.

Frithjof Küpper, of the Scottish Association for Marine Science, who led the research, saidthat the salt helped to neutralise ozone in the atmosphere and, as it rose, “these chemicals act as condensation nuclei around which clouds may form”.

Kelp is found in large quantities in the Hebrides, Robin Hood’s Bay in North Yorkshire and Anglesey. Scotland’s kelp beds are among the most extensive in Europe, with the Western Isles and Orkney archipelago among the main centres of soda ash production.

In the 18th century seaweed was burned to obtain soda ash, which was used in glass-making and construction. Alginate is still used to thicken products such as ice cream, jelly, salad dressing and toothpaste.

Kelp plays an important antipollution role in the removal of ozone close to the Earth’s surface.

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