北纬63度的日晕

2022年12月21日

Sun Halo at Sixty-three Degrees North
Image Credit & Copyright: Goran Strand

Explanation: Happy Solstice! Today is the December solstice, marking an astronomical beginning of summer in the southern hemisphere and winter in the north. On its yearly trek through planet Earth’s skies, at this solstice the Sun reaches its southern most declination, 23.5 degrees south, at 21:48 UTC. About 4 days ago the Sun was near this seasonal southern limit and so only just above the horizon at local noon over Ostersund in central Sweden. This view looking over the far northern lakeside city finds the midday Sun with a beautiful solar ice halo. Naturally occurring atmospheric ice crystals can produce the tantalizing halo displays, refracting and reflecting the sunlight through their hexagonal geometry. Still, with the Sun low and near the horizon in the clear sky, likely sources of the ice crystals producing this intense halo are snow cannons. Operating at a local ski area, the snowmaking machines create a visible plume at the top of the nearby island Froson toward the right side of the panorama.

Tomorrow’s picture: northern spiral

北纬63度的日晕
图像提供与版权: Goran Strand

说明: 欢庆冬至！今天是冬至（注：+8时区落在22日晨5:48），这个至点标志了天文学上南半球夏季和北半球冬季的起点。在地球天空每年的视运动之中，太阳在世界时UTC 21:48，来到南天赤纬23.5度的最南位置。4天前从瑞典中部的厄斯特松德镇看出去，往冬季最南点靠的太阳，在当地中午时几乎是贴在地平线上。在这张幅俯瞰这座极北滨湖城市的图像里，正午的太阳带着美丽的冰晕。自然界的大气冰晶，其六边形的几何结构能折射和反射阳光，并产生多种美丽的冰晕。话虽如此，但当时天空晴朗，而且太阳紧贴着地平线，因此能产生这例迷人冰晕的源头只可能是雪炮。在这幅全景图里，当地雪场运行中的造雪机，产生了右侧邻近福洛森岛上方的羽状雪尘即可为证。

明日的图片: northern spiral