the Place of a green plant in nature economy. Radiant energy

you are: the Place of a green plant in nature economy

When in thermonuclear ' to a fire chamber ' the Sun hydrogen turns to helium, energy is liberated in the form of radiation of various kinds. These different kinds of radiation forming a continuous spectrum energy, differ on lengths of waves (fig. 1.3). It is convenient to express lengths of waves in nanometrah (one nanometr is a milliard part of metre, 10-9. The visible part of a spectrum covers lengths of waves from 400 to 700 nanometers. (At some people the susceptibility threshold from outside short and long waves is a little shifted, but as averages the specified limits can be accepted.) The bottom limit (400 nanometers) corresponds to the blue-violet end of a spectrum, and top (700 nanometers) - to its red end; separate colours of a spectrum settle down in a following order: violet, dark blue, green, yellow, orange, red. Plants perceive radiations almost precisely in the same interval of lengths of waves, as a human eye if only not to consider some groups of the bacteria, capable to use the infra-red beams invisible to an eye.

In our century beginning German physicist Max Planck has established that radiant energy exists in the form of separate ' portions ', or quanta (differently photons), and that energy of these quanta is directly proportional to frequency of radiation.

As speed of distribution of all kinds of radiation is identical (3-1010 sm/c), and product of frequency of radiation for length of a wave of equally velocity of light frequency of radiation can be defined on length of a wave and ' on the contrary. Clearly that the more length of a wave, the more low frequency and the less energy of quanta. So, the quantum of ultra-violet radiation possesses bolshej energy, than quantum of dark blue light, and last in turn bears this more energy, than quantum of red light.

At impact with any molecule the quantum of radiant energy can be absorbed this molecule. As a result of absorption of energy the molecule passes in ' the raised condition ', and in such condition it appears capable to enter reaction which was actually impossible when it was at lower power level for this molecule. To cause certain chemical reaction, the quantum should possess the energy exceeding a certain critical size, characteristic for the given reaction. Quanta of x-ray and short-wave ultra-violet beams can to beat out, for example, from atoms elektrony, transforming atoms into ions. Quanta of visible area of a spectrum bear less energy and are not capable to cause ionisation; however if they are absorbed by pigments hloroplastov they can osushchest twist transformation СО2 into glucose. Quanta of an infra-red (thermal) range are not capable to cause any of these reactions, but they can cause other reorganisations of molecules demanding smaller quantities of energy.

Solar radiation, rather difficult on the structure, reaches surfaces of the Earth in strongly changed kind. For example, the atmosphere ozone layer (' an ozone board of the Earth ') intensively absorbs ultra-violet beams. It is rather favorable fact because if ultra-violet radiation reached a terrestrial surface not weakened it strongly would damage all live on our planet. Recently some scientists state fears that the ozone board of the Earth can appear partially destroyed as a result of activity of the person, in particular under the influence of exhausts of supersonic planes and owing to accumulation in atmosphere ftororganicheskih the connections used in aerosol cylinders. Such effect would have, of course, fatal consequences for a life on the Earth. Infra-red radiation of the Sun is absorbed by water steams mainly present at atmosphere, and also to some extent carbon dioxide though its maintenance in atmosphere is very insignificant; thanks to this absorption the temperature on a surface of the Earth is supported in the limits comprehensible to live organisms. Passes through atmosphere and reaches surfaces of the Earth mainly that radiation which corresponds to visible and infra-red areas. This radiation makes a basis of power of all live systems on the Earth. A certain part of this radiant energy catch and reserve in the course of photosynthesis green plants.