first day of winter 2009
Monday, November 30th, 2009In the Northern Hemisphere, the solstice that occurs in December marks the official, astronomical start of winter. [...] Indeed, if you have been watching the sun during sunrise and sunset over the past few months, you will have noticed it rising and setting farther and farther south each day. [1]
This corresponds to the months of December, January and February in the Northern Hemisphere, and June, July and August in the Southern Hemisphere. [2]
The winter solstice that occurs in December for the Northern Hemisphere is the summer solstice for the Southern Hemisphere. [...] In the winter time, those in the Northern Hemisphere receive fewer hours of sunshine and less direct rays of sunshine, which combine to make it the coldest season. [1]
Meteorologically, the winter solstice, being the day of the year which has fewest hours of daylight, ought to be the middle of the season, but temperature lag means that the coldest period normally follows the solstice, so the season is regarded (in the USA and England) as beginning at the solstice and ending on the following equinox. [...] The Earth is tilted at an angle of 23.44? to the plane of its orbit, and this causes different latitudes on the Earth to directly face the Sun as the Earth moves through its orbit. [...] Meteorological winter is the season having the shortest days and the lowest average temperatures, which have the coldest weather. [2]
It is understandable to wonder why, if the December solstice marks the shortest day and the farthest south the sun will get, that it hasn’t been colder leading up to the solstice and that it doesn’t get warmer more quickly as the sun moves north again. [1]
The coldest average temperatures of the season are typically experienced in January in the Northern hemisphere and in June or July in the Southern hemisphere. [2]
In the summer, it takes the atmosphere a while to warm up from receiving the additional radiation, and therefore it is not hottest at the summer solstice. [1]
Please help improve this article by adding reliable references. [2]
The copyright of the article First Day of Winter in Solar System Astronomy is owned by Kelly Whitt. [1]
Other annual plants require winter cold to complete their life cycle, this is known as vernalization. [2]
In actuality, the sun has not been moving farther south but the Earth has been orbiting the Sun. [1]
Sources:
[1] First Day of Winter: When the December Solstice Occurs …
[2] Winter - Wikipedia