Last year, October 16, the Sun in the south of Great Britain turned into a dull red-orange spot. Meteorologists quickly found out the reason for the unusual phenomenon, explaining it by dust emissions from the Sahara desert and the Iberian Peninsula, caught in a cyclone from Hurricane Ophelia.
The new study presents dust analysis results that can help improve weather forecasts.
A team of scientists from the Universities of Redins and Baths in the United Kingdom observed the dust cloud at several UK meteorological observatories, where they were able to sample the dust and measure how it deflects a laser beam.
“Dust scatters some colors of sunlight more than others. The reddening of the sun was caused by the predominant scattering of blue light in an optically thick plume,”the report says.
A lightning detector from one of the sites was used to measure the increase in the electrical charge of the cloud.
According to the data obtained, dust particles could not only obscure the Sun, but also affect the clouds formed on that day. Falling electrically charged particles can accumulate more water molecules, which are shaped such that they have much more charge on one side than the other, and therefore tend to be attracted to the other matter. Indeed, a descending cloud was recorded at one of the observation sites some time after the appearance of dust clouds.
Dust plumes usually contain an electrical charge due to collisions and friction between particles. Considering the important role of such aerosol particles in weather processes (they can become cloud nuclei), their electric charge requires special study. Even at the Large Hadron Collider, an experiment is underway to measure how various properties of dust particles, such as their size and composition, can affect clouds. Although the electrical properties of dust have been observed for quite some time, its electrical effects are still not taken into account in atmospheric numerical models.
The study is published in Environmental Research Letters.
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