The article tells about what winter is, what it happens, depending on the place on the planet, and why there are changes of seasons.
Seasons
Life on our planet has existed, according to some estimates of scientists, for more than 3 billion years, and in our entire solar system, only the Earth is lucky to have certain conditions for the development and maintenance of biological life. There are many such factors. This is the presence of liquid water, a certain distance from the central star, gravity, atmosphere, etc. But, there is another factor, this is the rotation of the planet around its axis, due to which the seasons change. How are they connected? Very simple, consider an example of the same Mercury. This planet is too close to the Sun, and, besides, it always faces one side, which is why on the sunny side the temperature reaches almost 500 degrees Celsius, and at night there is eternal darkness and cosmic cold. So, as you can see, the seasons are very important. And in this case we will talk about winter. So what is winter?
Definition
First, let's deal with the terms. Winter is a cold season, in which the temperature stably stays below zero degrees Celsius and often snow falls. If we take the calendar winter, then in the northern hemisphere it lasts 3 months - December, January and February. And in the south - July, June and August. So now we know what winter is. However, why does it arise?
Axis tilt
It is all about celestial mechanics, how the planet rotates. With a certain periodicity, the Earth changes the axis of rotation of the axis relative to the plane of the ecliptic, therefore, the northern hemisphere receives less solar heat, because of which the average daily temperature gradually drops, and at the time of its stability below 0 degrees, the actual winter time sets in. This is called an astronomical winter, in the northern hemisphere it lasts from December 22 to March 21. So, we sorted out the question of what winter is.
Weather
Despite the dates of the astronomical and calendar winters, the cold season with a negative temperature and precipitation everywhere comes in different ways. For example, in the Russian village of Oymyakon, starting from August 31, thermometers often show negative temperatures, the same applies to other regions of Yakutia and Chukotka. Well, in Primorye and the Khabarovsk Territory, due to the proximity to the ocean, the climate is milder, and colds come, respectively, later.
Analyzing the question of what winter means, it is worth mentioning the ocean currents, which play a large role in the climate. For example, Holland, which is washed by the Gulf Stream, has a mild and temperate climate, while the same Chukotka, being with it almost at the same latitude, suffers most of the year from severe frosts and precipitation.
Eternal summer
There are zones on Earth where there is never winter. And the fact that the locals take it for cold will only cause a smile among the inhabitants of the northern hemisphere, and this is the equator. Again, due to the inclination of the earth's axis, the change of seasons almost does not occur there, but rainy seasons regularly occur.
Polar night and day
There are two very interesting phenomena both at the north and south poles, these are polar night and day. The polar night is considered the period when the sun has not been longer than a day, the same is with the day, only on the contrary - when the sun does not set all 24 hours. The duration of these phenomena strongly depends on the time of year and longitude, but the longest period of the polar night regularly lasts almost six months.
Despite the fact that people live for a long time with such phenomena, they nevertheless have an effect on a person both psychologically and physically. People often experience depression during the night and an acute shortage of vitamin D.
Thus, we examined what winter is, the definition of this word is also considered by us.