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Biometeorology: Weather and Health

Biometeorology is the study of the impact weather has on the natural world, including animals, plants and humans. This includes the impact on symptoms of existing diseases, contribution to new conditions and temporary physiological changes. There are a number of illnesses and symptoms that are caused or exacerbated by certain types of weather. Here we discuss some of the more obvious conditions, as well as some, perhaps, more surprising ailments.

How does hoar frost form?

Under clear, cold nights in winter, a hoar frost can form.

A hoar frost forms in a similar process to that of dew; the difference being that ice crystals are deposited, as opposed to water, because the temperature of the surface is below freezing.

Hoar frosts most commonly attach themselves to the branches of trees, leaves and grasses, but can also be seen on objects such as gates and flowerpots. Sometimes the deposits can be so thick that it may even look like a dusting of snow has fallen, creating a typical winter wonderland day.  

What causes these beautiful frost patterns?

Clear nights and plunging temperatures can deposit a thick frost by daybreak. For frost to form, the temperature of the surface must be below 0°C. But what causes these pretty, leaf-like patterns? The patterns are the result of very tiny imperfections on the glass, such as scratches, specks of dust and salt, or the residue from washer fluid. These variations in the surface affect the way that the ice crystals form and branch out, forming the beautiful patterns captured in this image, taken in North Yorkshire on an smartphone by Paula Davies. 

Cold snap wreaks havoc on African penguin population

The cold snap that hit South Africa in June, leading to incessant moaning from English football commentators who had failed to pack appropriately for the World Cup, had a far more malign impact on the nation's wildlife than it did on its showpiece sporting event. Around 600 African penguins, already an endangered species, were killed by the icy temperatures, heavy rain and significant wind chill over a two day period in mid-June on Bird Island, Algoa Bay in Eastern Cape province. The victims were mainly young chicks whose downy feathers provide scant protection against the elements.