Photo: Dmitry Rogulin/City News
Anatoly Sudakov found a strong confirmation of this.
Those who consider September to be an autumn month are wrong. In fact, the first two decades of September are the end of the astronomical summer, which ends on the day of the autumnal equinox, and not at all the last day of August! So we meet the beauty of autumn, far from being as young as the beauty of spring, but beautiful in its own way, pleasing with the generous gifts of nature, “The crystal clear calm of the Indian summer”, the ripe colors of the yellowing. foliage. But with each week, the “glamour of the eyes” wrinkles more and more often, cries from heavy rains and brings with it sad thoughts that another year is ending, as we have grown older. The nature of autumn depends on the geographical location of the area. About when autumn begins and ends and what it looks like in the Lower Volga region, City News asked Russian climatologist Anatoly Sudakov.
That time has not come!
When we say the name of the current month, we do not think about the meaning of the word “September”. But the names of the months of the year came to us from the Latin language. September (from the Latin ordinal “septimus”) means “seventh”, October (from “octavus”) – the eighth, November (from “nonus”) – the ninth, December (from “decimus”) – the tenth.
But excuse me, September is the ninth month of the year, and December is generally the twelfth! Why don’t the names of the months match their serial numbers in the calendar?
– But the fact is that before Octavianus Augustus in republican ancient Rome, where the names of the months appeared, there were ten of them in the calendar. After the end of the tenth month, the counting of days until the vernal equinox ceased and then began again. First there were three spring months, then three summer months, then three autumn months. This is how the tradition of considering September as an autumn month arose, – says Anatoly Sudakov.
The concept of “calendar autumn” does not correspond to astronomical realities. From the point of view of celestial mechanics, autumn comes at the hour when the Earth’s orbit crosses a point equidistant from the position where it was in orbit on the day of the summer solstice, and the one where it will be during the winter solstice. This day is called the autumnal equinox. School geography teachers told and continue to tell our children and grandchildren that these days compare the duration of daylight and nighttime. And this is one of the most common misconceptions driven into our heads during natural history lessons.
Equivalent? see more!
There are actually no days when the duration of daylight compares to the duration of darkness (when the sun is below the horizon). And the smallest difference between the day and night parts of the day falls on a later date. There is a reason for this, which is called a false sunrise and a false sunset. Due to the refraction of the sun’s rays by the earth’s atmosphere, which has not yet risen from the horizon or has just sunk beyond its line, we see the sun in the sky for several minutes, when it is still or no longer there.
The autumnal equinox is not a geographical, but an astronomical concept, indicating the moment when the center of the sun’s disk crosses the celestial equator in the apparent movement of the sun across the celestial sphere. In 2022, it will take place on September 23 at 01:03:40. according to the Universal Time of the Greenwich Meridian. The equinox occurs at the same time at all points on the Earth’s surface, only in the southern hemisphere at the specified time will the vernal equinox occur, and in our northern hemisphere – autumn. And as for the duration of daylight, it will be the same only at the same geographical latitude.
On the day of the autumnal equinox, sunrise in Volgograd comes at 05:50, sunset at 17:57. The length of daylight will be 12:07:19. Consequently, 11 hours 52 hours 41 seconds will remain in the night. Not very regular intervals, is it? The minimum difference between the duration of darkness and daylight will be on September 25. It will be 13 pp. in favor of daylight. And only on September 26, the night will win by a score of 03 m. 20 s. And from this day, the duration of the dark time of the day will increase by more than three minutes on each date until the arrival of the winter solstice.
The last gift of the last summer
Saying goodbye to summer is always sad. In September, the mercilessly scorching sun and the numbing heat are already beginning to be forgotten. The temperature in August was above the norm by 4.3 °С. Volgograd saw global warming in the eye. Due to the fact that August this year became the hottest month of the year, the Earth’s surface has accumulated large heat reserves, with which it warms the air next to it at night. This keeps warm nights and even warmer days. There is little diurnal variation in temperature with a difference between day and night temperatures of only a few degrees. And although the polar front cyclones of the first and early second decade brought a cooling to Volgograd, after their influence ceased, warming set in again, until the heat of September 18, when the maximum daily temperature rose to 28.3 °C.
Thus, the cooling was due to circulation factors associated with the transfer of cool air masses by cyclones from Northern Europe to the Lower Volga region along the polar front. And the current warming is due to radiation factors, that is, radiation at night from the Earth’s surface of heat to outer space. This factor will continue to work for some time, thanks to which there are conditions for a long, albeit intermittent, “Indian summer” in the first half of October.
Warm and moist
Strictly speaking, the classic Indian summer, with two to three weeks of calm, clear weather and daytime temperatures of 10-15 °C, is typical of the zonal epoch of atmospheric circulation, which ended in the middle of the last decade. This weather period corresponds to the central part of anticyclones, which in early autumn can have a diameter of three to four thousand kilometers. And even on their outskirts the weather was quite calm and stable. But now the era of meridional atmospheric circulation is underway and the “Indian summer” will be so-so: warmer, but rather gloomy. On September 19, an atmospheric front with moderate precipitation passed through Volgograd. Frontal type cloudy weather with moderate precipitation will remain in the third decade. Until the end of the month, winds with southerly and westerly components will prevail, bringing tropical sea air to our region.
– In the first half of October, when a stable seasonal anticyclone forms over Western Siberia, the weather will clear up, but there will be no significant cooling due to the continued release of heat from the geographical surface of the Lower Volga region, – says the scientist. – And periodic transgressions of marine tropical and marine polar air in the approximate direction of the meridian will cause temperature fluctuations while the weather is predominantly cloudy and cloudy. Generally speaking, conditions are created for a warmer October, compared to the long-term norm.
Until the light!
At the same time, the Earth continues to rapidly approach the Sun. On July 5, the center of our planet was 152 million 98 thousand 497 km 167 m from the center of the Sun. On the day of the autumnal equinox, this distance will decrease to 150 million 128 thousand 276 km 197 m and will continue to decrease until January 4, when it will be minimal – 147 million 98 thousand 916 km 669 m. However, this will not affect the winter nature in some way.
– At such distances as in the solar system, five or six million kilometers does not make the weather. It will be determined by other factors, primarily global warming, which has not only not stopped, but has accelerated significantly since the beginning of this century. In particular, in Volgograd, between 2000 and 2020, the average annual temperature increased by 0.5 °C. Moreover, in the first decade, the warming most affected such months as February, March, August and November, in the second – May, June and August. Approximately one and a half to two weeks extended the duration of the phenological fall. And the real winter will be exotic, – Anatoly Sudakov describes the situation.