What are the Earth's illumination belts
All living things on Earth directly depend on the Sun. Even deep-sea fish, blind from birth and perfectly avoiding light, will not 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 reason is the first
However, light and heat come to the surfaceThe Earth is not in the same number. There are several reasons for this. First of all, the planet has a nearly 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, the Earth heats up and is illuminated more strongly. Where the sun's rays touch the planet in passing, it's much cooler.
Uneven heating and lighting: factor number two
The second reason is that our "ball" is in orbitIt moves not vertically, its axis has some inclination to the ecliptic. This angle of inclination leads to the fact that heating and lighting become uneven. If the axis is perpendicular to the plane along which the Earth is circling around the Sun, the day and night would be the same duration, and the time of the year would always be the same.
These factors and cause the existence of certain zones, which are called "Earth's illumination belts."
Depending on the magnitude of the angle of incidence of the raysThe earth is also climate, and the duration of the night-day, and the average annual air temperature, and, accordingly, the "set" of plants and animals inhabiting a certain zone. So how many illumination belts on Earth? They are distinguished by three main, but two of them (hot and polar) are divided into two (northern and southern). So if you comply with this unit, then the question of how many belts of illumination, it will be correct to answer - five.
The hottest is tropical. If we consider the belt of illumination of the Earth as a percentage, then the hot one will take forty percent of the entire surface. It is characterized by the warmest climate, the change of seasons even occurs, but there are no sharp differences between, say, between winter and summer, day and night are almost the same in duration. The sun during the year in the zone of this belt of illumination of the Earth twice occurs at its zenith (March 21 and September 23, when we have the spring and autumn equinox), and rises above the horizon for the rest of the time.
If we recall the hypothetical assumption ofthe vertical axis of the planet's axis to the ecliptic, there would not be much change in relation to the tropics, because in the existing conditions, the sun's rays are falling almost perpendicularly.
It takes up more than half of our planet ifto observe the extreme accuracy, then 52 percent. A feature of this belt of illumination of the Earth is a clear change of seasons in most of the territory that it occupies. The duration of night and day in these latitudes depends on the time of the year: in winter, the longer the dark time of the day, in the summer - daytime.
Closer to the polar circles is a phenomenon,called the white nights, when the luminary hides for a very short time beyond the horizon, because of which the evening dawn gradually turns into the morning sun. It's not dark at night like this, and at midnight you can see almost like the day.
For the moderate belt of illumination of the Earth is also characteristic that the Sun in it never reaches the zenith.
The change of seasons is conditioned by the differencevegetation from the tropical. If the latter is green all year round, then most of the bushes and trees in the cold months "fall asleep", that is, discards the leaves and stops growing. Some species of animals also hibernate for the winter, which does not happen in a hot belt.
December 22 and the same date in Junethe fact that day and night in these dates are the longest. So, on December 22, the night takes a longer time of the day, and in the following days it slowly decreases. And on June 22 the day is longer than the night; but then it contracts, preparing the nature for a winter sleep. Interesting from the astronomical point of view is also March 21 and September 23, when day and night are equal among themselves.
These are the smallest areas of all. They occupy only eight percent of the planet Earth. In other words, they are also called polar, which describes their location very accurately: these belts of the Earth's illumination on the map coincide with the North and South poles.
Winter and summer here actually coincide with the night andin the afternoon: in the winter months the sun is completely absent in the sky, in the summer months it does not go away. In addition, it should be noted that the summer is very short, and although the light does not hide behind the horizon, it practically does not heat the earth. Its rays almost do not touch the surface - too sharp an angle of their fall. It can be said that the white nights observed in the temperate zone are the vestibule of the polar days and nights.
Cold and low light determined the scarcityflora in the polar belts. The closer to the center of the belt, the less vegetation. If there are even moss in the circumpolar circles, even he does not survive on the poles. The same applies to animals. The further from the pole - the greater the diversity.
In general, it is easy to see that the belts of the Earth's illumination have a very strong effect on the habitat of all living creatures of the planet.