Finnish meteorologists were surprised by unusual images on radar observation maps on Wednesday morning. They were not explained by weather phenomena.
Beginning on Tuesday, a spherical pattern took shape to the west of Finnish Lapland, over northern Sweden. It was hundreds of kilometres across.
From the northeast corner of the spherical pattern, streaks on the map seemed to flow into Finnish Lapland, which appeared as rain. However, there was no precipitation in the area, Yle meteorologists confirmed.
The cause of the spherical pattern was apparently a faulty weather radar. The pattern centred on the Kiruna radar station, some 200 km west of Muonio, Finland.
Meanwhile the "rain" most likely originated from a military exercise.
The Finnish Air Force is taking part in an ongoing military drill in the northern parts of Finland, Sweden and Norway. The unusual observations match the general training area.
Air forces around the world spread chaff, a fine metal-containing substance, into the air during exercises and warfare in order to thwart enemy radars. It can appear on weather radar images as precipitation.
The current exercise is Finland's first collective defence drill as a Nato member, with Sweden expected to formally join the alliance next week.
7.3: Satellite reference removed from headline.
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