Frosted nature
Text: Vello Keppart
Photo: Arne Ader
Translation: Liis
Frost in lime tree crown.
The landscape is as a winter fairy tale – the leafless trees and bushes are dressed in hoar frost; a broadleaf forest can’t even be seen through any more, the needles of larches have been replaced by ice crystals. Ever more hoar frost collects in daytime, branches and needles are covered by a several centimetres thick layer of ice crystals. How does hoar frost come about? What is the difference between crystalline hoar frost and rime frost - READ HERE (in Estonian) or HERE .
According to data from the weather stations in Estonia the hoar frost started in the Pandivere highlands (Väike-Maarja) already on January 7; on January 10 and 11 the frost could be admired nearly all over Estonia. The morning of January 11 was particularly beautiful – frosted trees, sunshine, and a deep blue, clear sky as a backdrop. On January 14 the weather stations reported slight hoar frost (length of crystals up to 14 mm) in Kuusiku, Viljandi, Virtsu, Kihnu, Valga, Võru, Jõgeva and Narva-Jõesuu; medium frost (15-50 mm) beginning on Sunday in Pärnu and on Monday in Harku; severy hoar frost (more than 50 mm) beginning on Tuesday in Väike-Maarja and Tartu (Tõravere). Pity that hoar frost is registered, but not measured by all weather stations; one has to do that for oneself.
Hoar frost is a hazard when the frost layer is more than 20 mm, and a severe hazard when it is above 50 mm.
Snow and frost on trees puts an additional weight on branches that should be shaken off from valuable trees and bushes in the garden. Particularly at risk are the column, pyramid and globe varieties of thujas. Large trees with thick trunks are not in danger, but trees that have grown tall and thin through lack of light bend; from this bending by snow the trees can break. However, knocking on the trunks can damage the cambium layer under the bark significantly, and the tree can become diseased from the damage or even fall. In dry air and frost, the green needles of spruces are at risk. Only hoar frost saves the shoots of spruces from drying in winter.
Unless the wind blows the frost off the trees, we can hope for a weekend in Estonia with sunshine on a frosted landscape, to admire and photograph.
According to data from the weather stations in Estonia the hoar frost started in the Pandivere highlands (Väike-Maarja) already on January 7; on January 10 and 11 the frost could be admired nearly all over Estonia. The morning of January 11 was particularly beautiful – frosted trees, sunshine, and a deep blue, clear sky as a backdrop. On January 14 the weather stations reported slight hoar frost (length of crystals up to 14 mm) in Kuusiku, Viljandi, Virtsu, Kihnu, Valga, Võru, Jõgeva and Narva-Jõesuu; medium frost (15-50 mm) beginning on Sunday in Pärnu and on Monday in Harku; severy hoar frost (more than 50 mm) beginning on Tuesday in Väike-Maarja and Tartu (Tõravere). Pity that hoar frost is registered, but not measured by all weather stations; one has to do that for oneself.
Hoar frost is a hazard when the frost layer is more than 20 mm, and a severe hazard when it is above 50 mm.
Snow and frost on trees puts an additional weight on branches that should be shaken off from valuable trees and bushes in the garden. Particularly at risk are the column, pyramid and globe varieties of thujas. Large trees with thick trunks are not in danger, but trees that have grown tall and thin through lack of light bend; from this bending by snow the trees can break. However, knocking on the trunks can damage the cambium layer under the bark significantly, and the tree can become diseased from the damage or even fall. In dry air and frost, the green needles of spruces are at risk. Only hoar frost saves the shoots of spruces from drying in winter.
Unless the wind blows the frost off the trees, we can hope for a weekend in Estonia with sunshine on a frosted landscape, to admire and photograph.
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