Winter SolsticeDecember 21st, 2012 at 12:02 am by Bill Steffen under Bill's Blog, Weather
<–click to enlarge – (graphic from UCAR and the Univ. of Michigan). Today (Fri) at 6:12 AM we have the Winter Solstice. So, today is the shortest day of the year (least amount of available daylight) in the Northern Hemisphere and the longest day of the year in the Southern Hemisphere. The word “Solstice” is Latin for “sun stands still”. Today the sun is directly overhead at solar noon at a latitude of 23 degrees and 26 minutes south latitude, a line called the Tropic of Capricorn. In Grand Rapids we have nine hours of daylight today (sunrise 8:11 AM, sunset 5:11 PM). There is less daylight the farther north you go. At Sault Ste. Marie (sunrise 8:18 AM, sunset 4:35 PM – note the difference is mainly in the sunset time), they get 8 hours and 17 minutes of available sunlight. North of the Arctic Circle, the sun stays below the horizon all day long. At Barrow, Alaska the top tip of the sun won’t climb above the horizon until Jan. 22 and at the North Pole not until the Spring Equinox in March. The gain in sunlight is slow at first. In the next month we gain only 34 minutes of daylight (4 minutes in the morning and 30 minutes in the evening), with a more rapid increase in daylight around the Spring Equinox. Temperature lags the position of the sun by around one month, so the coldest temperatures in the Northern Hemisphere on average occur around January 21. Happy Winter to all!