夏至Summer Solstice
简介
中国民间把夏至后的15天分成3“时”，一般头时3天，中时5天，末时7天。这期间我国大部分地区气温较高，日照充足，作物生长很快，生理和生态需水均较多。此时的降水对农业产量影响很大，有“夏至雨点值千金”之说。
夏至节气一般在公历6月21日或22日。夏至为者，至有三义；一以阴阳气之至极，二以明阳气之始至，三以明日行之北至。故为至。《月令七十二候集解》关于夏至说：五月中，夏，假也，至，极也，万物于此皆假大而至极也。
Summer Solstice
The traditional Chinese lunar calendar divides the year into 24 solar terms. Summer Solstice, (Chinese: 夏至), the 10th solar term of the year, begins on June 21 this year and ends on July 6.
At this time, much of the northern hemisphere receives the most hours of daylight, but it does not bring the hottest temperatures which will come only 20 to 30 days later.
In China, the 24 solar terms were created thousands of years ago to guide agricultural pr
oduction. But the solar term culture is still useful today to guide people's lives through eating special foods, performing cultural ceremonies and even healthy living tips that correspond with each solar term.
三候
中国古代将夏至分为三候：“一候鹿角解；二候蝉始鸣；三候半夏生。可见夏至一到阴凉就不远了。
节气特点
夏至是北半球一年中白昼最长、黑夜最短的一天。夏至日那天，整个地球上除南极点和南极圈内的极夜地区外，所有地点的日出方向都是从东北方开始的，在西北方落下。
“天文专家称，夏至是太阳的转折点，这天过后它将走“回头路”。夏至过后，太阳直射点逐渐向南移动，北半球白昼开始逐渐变短。对于北回归线及其以北的地区，夏至日过后，正午太阳高度也开始逐日降低。民间有“吃过夏至面，一天短一线”的说法，我国唐代诗人韦应物的《夏至避暑北池》也曾写到“昼晷已云极，宵漏自此长”。
夏至这天虽然白昼最长，太阳角度最高，但并不是一年中天气最热的时候。因为，接近地表的热量，这时还在继续积蓄，并没有达到最多的时候。俗话说“热在三伏”，真正的暑热天气是以夏至和立秋为基点计算的。大约在七月中旬到八月中旬，中国各地的气温均为最高，有些地区的最高气温可达端午节的由来和风俗简介40度左右。
“不过夏至不热”，“夏至三庚数头伏”。夏至虽表示炎热的夏天已经到来，但还不是最热的时候，夏至后的一段时间内气温仍继续升高，大约再过二三十天，一般是最热的天气了。夏
至以后地面受热强烈，空气对流旺盛，午后至傍晚常易形成雷阵雨。这种热雷雨骤来疾去，降雨范围小，人们称夏雨隔田坎。唐代诗人刘禹锡在南方，曾巧妙地借喻这种天气，写出东边日出西边雨，道是无晴却有晴的著名诗句。
The longest day of the year
On the Summer Solstice itself, daylight lasts the longest for the whole year in the northern hemisphere. After this day, daylight hours get shorter and shorter and temperatures become higher in the northern hemisphere.
How long is the longest day in China? According to the expert Yan Jiarong, the entire day in Mohe in Helongjiang province, located in the northernmost tip of China, lasts nearly 17 hours when you include dawn, twilight and its afterglow. Summer Solstice is the best season for viewing the aurora in Mohe, "the sleepless town of China".