Friday, 25 February 2011

More elliptical halos

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Ari Laine photographed this elliptical halo on 24 February in Lahti. It was already third occurrence within two weeks in Finland. This time the ellipse is more like an elliptical glow rather than well defined ring, but outside the glow above the sun there might be a faint ring visible (one has to be cautious about jpg artefacts).  During the last two weeks the conditions have been favourable for ellipses in Finland as it has been clear skies and around -15° C temperatures during the daytime, which is the optimal temperature for the elliptical halo crystal formation. In this case the temperature on the ground was -16° C, but the ellipse formed in an ice crystal layer that slightly above the ground. In Tampere similar crystal layer situation was observed as well, however, the halos were the usual stuff.

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