据维基百科文章突然平流层变暖,>平流层的辐射周期意味着冬季>平均流量是西风,在夏季是伊斯特利(西)。>最终变暖发生这种转变,所以,极地漩涡>风改变方向的变暖,但是不改变>直到那年冬天。这是因为平流层>已进入夏季东风阶段。最后是因为另一个变暖>不能发生在夏季,所以最后的变暖>现在的冬天。类似地,隶属美国航天宇航局的[源](http://ozonewatch.gsfc.nasa.gov/facts/warming_NH.html)说,>最后变暖是最后平流层变暖的季节。>后变暖,平流层从来没有恢复到以前的>状态,涡破裂和消散。最后变暖经常>发生在3月或4月。有时平流层从未恢复>从深冬,原本是一个主要的变暖在一月或者二月>,,气候变暖成为最后的变暖。据我理解,极涡破裂后,一个人不能有突然大温度下降(像我们(2016年4月2 - 3日,本周末)(http://nymag.com/daily/intelligencer/2016/03/polar-vortex-is-visiting-nyc-this-weekend.html)。因此看起来,最后变暖的日期是一个很好的候选人进行正式的结束日期”气象冬季”。 However, NOAA defines seasons according to calendar months (see www.ncdc.noaa.gov/news/meteorological-versus-astronomical-summer%E2%80%94what%E2%80%99s-difference ). Meanwhile, the Swedes define the start of spring as "when the average daytime temperature exceeds zero degrees Celsius on seven consecutive days" (see www.thelocal.se/20090313/18200 ). So, why isn't the end of winter defined as the date of the final warming? Yes, one could not know that it happened until some time after it happened, but my understanding is that this lag is on the order of days, not weeks. (And by the way--and I know this is off topic, but still---why don't the media report the date of the breakup of the polar vortex? It seems it would be of interest to people, given the notoriety the concept has received especially the last couple of winters... In fact, is the date reported anywhere?)