All life on Earth is directly dependent on the sun.Even deep-sea fish, blind from birth and well dispensed with light, cannot survive without the heat that our star supplies to the planet. Neither plants, nor bacteria, nor highly organized organisms can exist without the energy that the sun gives.
Uneven heating and lighting: the first reason
However, light and heat come to the surface.Earth is not in the same amount. There are several reasons for this. First of all, the planet has an almost spherical shape (albeit slightly flattened from the poles). Accordingly, the rays of our Sun reach the earth's surface at different angles. Where the angle of incidence is closer to the straight line, the Earth heats up and illuminates more strongly. Where the sun's rays touch the planet casually, it is much cooler.
Uneven heating and lighting: factor number two
The second reason is that our "ball" in orbitdoes not move vertically, its axis has a certain inclination to the ecliptic. This angle of inclination causes the heating and lighting to become uneven. If the axis were perpendicular to the plane along which the earth revolves around the sun, the day and night would be the same length, and the time of year would always be the same.
These factors determine the existence of certain zones, which are called “Earth’s illumination belts”.
Hot belt
Depending on the magnitude of the angle of incidence of rays onThe earth is located and the climate, and the duration of the night-day, and the average annual air temperature, and, accordingly, the "set" of plants and animals that live in a certain area. So how many illumination belts on Earth? They are distinguished by three main ones, but two of them (hot and polar) are divided into two more (north and south). So, if you follow this division, then the question of how many light belts will be answered correctly is five.
Самый жаркий – тропический.If we consider the belt of illumination of the Earth as a percentage, then the hot one will occupy forty percent of the entire surface. It differs in the warmest climate, although the seasons change, although there are no sharp differences between, say, winter and summer, day and night are almost the same in duration. During the year, the sun in the zone of this Earth’s illumination zone occurs twice in the zenith itself (March 21 and September 23, when we have the spring and autumn equinox, respectively), and rises high above the horizon the rest of the time.
If we recall the hypothetical assumption ofif the axis of the planet is vertical to the ecliptic, then with respect to the tropics, little would change, because under existing conditions the sun's rays here fall almost vertically.
Temperate zone
Он занимает больше половины нашей планеты, если comply with the ultimate accuracy, then 52 percent. A feature of this Earth’s illumination belt is a clear change of seasons in most of the territory it occupies. The duration of night and day in these latitudes depends on the season: in winter it is longer than dark, in summer it is daytime.
Closer to the polar circles there is a phenomenoncalled the white nights, when the light is very briefly hiding behind the horizon, because of which the evening dawn smoothly passes into the morning. On such nights it doesn’t get dark, and at midnight it’s almost like daytime.
For the temperate zone of the Earth’s illumination, it is also characteristic that the Sun never reaches its zenith in it.
Change of seasons causes and differencevegetation from tropical. If the latter is green all year round, then here most of the bushes and trees “fall asleep” during the cold months, that is, it leaves the foliage and stops growing. Some species of animals also hibernate for the winter, which is not the case in a hot belt.
December 22 and the same number in June are significantthe fact that day and night on these dates are the longest. So, on December 22, the night takes more time of day, and in the following days it gradually decreases. And on June 22, the day is longer than night; but then it contracts, preparing nature for winter sleep. Interesting from an astronomical point of view is also March 21 and September 23, when day and night are equal.
Cold belts
These are the smallest zones of all.They occupy only eight percent of the planet Earth. In another they are also called polar, which very accurately describes their location: these belts of the Earth’s illumination on the map coincide with the North and South poles.
Winter and summer here actually coincide with night andin the afternoon: in the winter months the Sun is completely absent from the sky, in the summer months it does not leave it. In addition, it should be noted that the summer here is very short, and the light, though not hiding behind the horizon, practically does not heat the earth. Its rays almost do not touch the surface - their angle of incidence is too sharp. It can be said that the white nights observed in the temperate zone are the threshold of polar days and nights.
Cold and low light determined the povertyflora in the polar zones. The closer to the center of the belt, the less vegetation. If in polar circles there is at least moss, then even he does not survive at the poles. The same applies to animals. The farther from the pole - the greater the variety.
In general, it is not difficult to notice that the Earth’s illumination belts have a very strong effect on the habitat of all living creatures on the planet.
