Birds and insects are filtered out of public weather images. However, the movements of migratory birds are recorded in weather radars.
Little birds The migration rush was clearly visible on the weather radar at the turn of the week.
At that time, the birds started moving in large numbers as the weather cooled down, a researcher at the Finnish Meteorological Institute Mika Rantanen tells.
“For example, willow birds and other insectivores are very abundant in Finland, which is why they are observed a lot in surveys,” says Rantanen.
It is difficult to spot them anywhere else, because the migration takes place at night.
In the video shared by Rantanen, the blue areas are birds that have taken off and have reached the detection range of the radar beam. In the north, the areas turn blue later, because the sun sets first in the south. Many little birds do not leave until dark.
Yellow and Orange areas are showers and thunderstorms.
Birdsinsects and airplanes end up in radar images using the same mechanism as rain: microwave radiation is emitted from the radar, which is reflected back when it hits something.
However, the radar images shown to ordinary trampers do not show birds.
“In weather monitoring, birds and insects are usually distractions that are filtered out of the images. However, there are radar images for research use where you want these to be visible,” says Rantanen.
The pictures are rough, so you can’t tell how many birds there are based on them. There can be dozens of different species. In addition to the willow birds, at the moment, at least rainbow jays, alder birds, grebes and grebes are likely to migrate.
Rantanen according to this, the moving time is by no means exceptional.
“It’s not surprising that they are blowing in the sky at this time,” says Rantanen.
However, the warm weather may have caused the so-called “migration dam”, which has now erupted. The eruption has been seen especially in the coastal areas of the south, where the birds pack up before leaving.
“They often follow the coasts, because they try to keep sea crossings as short as possible.”
The influence of the coast can be seen especially in the diurnal change.
The birds are probably on their way to Africa or the Indian region. The later the birds migrate, the further north they usually stay.
Adjustment 31.8. 21:05: Removed the wording from the title that the birds would have flown in flocks.
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