is hard to imagine that daylight lasts more than 24 hours, that he was not replaced at night and on the street permanently light.Or vice versa - all time of night, darkness, cold.But the way it is for the internal borders of the Arctic Circle.
Polar Day - a period during which the Sun is above the horizon and does not go for it more than one day.This phenomenon can be observed in the polar regions to the north of the Arctic Circle and south of the Antarctic Circle.
Polar day possible thanks to the inclination of Earth's equatorial plane relative to the plane of the ecliptic by approximately 23 ° 26 '.It lasts almost two days on the Arctic Circle and increases the higher latitudes to 186 days at the poles.The shortest it the latitude of about 65 ° 43 '.The longest - in the North and South Poles.There its duration is six months.At the North Pole, he begins March 17 and lasts until 25 September.And at the South Pole lasts roughly from September 20 to 22 March.During the polar day the sun does not come every day on the horizon, but makes a circle parallel to the horizon.In addition, the phenomenon of refraction makes it possible to observe the presence of the sun at the same time on both poles for several days in a row before and after the equinoxes.
near the outside of the polar circle there is polar night.During this period, there is no sun in the sky more than a day.Border constant night near the Arctic Circle is located at a latitude of about 73 ° 5 'to the South.This night can last a maximum of 178 days.
Start and duration of the polar days and nights are different for different localities.They also observed the different weather conditions.This is due to their location at a particular latitude.For example, in the north, Polar, the polar night lasts from 30 November to 13 January;Murmansk starts on December 2 and ends on January 11;Polar Zory (weather that winter is very severe) meets her on December 21 and escorted 23 of the same month.
As we have seen, these phenomena have a duration of about 186 - 178 days, that is, at the poles lasts half a day, six months - a night.And these periods are responsible for weather conditions on the ground.There does not exist the four seasons of the year, but only conditionally divided the summer (in the polar day) and winter (when it is the polar night).And what is happening to our planet during these periods?
summer one of the poles of the Earth facing the sun and does not go into the shadows, despite the planet's rotation around its axis.In this area - the polar day.But he is not the same as we used to see him.After all, it is not a part of the day, because it lasts for six months.Since the pole is directed to the luminary, then, accordingly, the sun is hiding behind the horizon, and moves along it.
At the opposite pole there is a completely different situation.Since that time, he nearly six months in the shadow, it goes on permanent night.The sun does not appear above the horizon.
Shortly before the onset of the polar day in the "gloomy" Pole appears a fascinating natural phenomenon - the aurora borealis.When it occurs around it becomes lighter as under the full moon.Northern Lights - just an optical effect, but what a spectacular!How many people dream at least once to see him live!
Northern Lights occur in the upper atmosphere by the interaction of the magnetic field of the Earth with cosmic particles.This emission of air at a height of 60 to 1000 km in the form of arcuate beams, curtains, crowns.It can be seen in both hemispheres of the poles, but with varying intensity, depending on the longitude.It lasts from several minutes to several days, and may occur at different times of the year only in the night sky.
