Soil

Soil is a natural body consisting of layers (soil horizons) of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and erosion. Soil differs from its parent rock due to interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere. It is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states.
Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil solution (liquid) and air (gas). Accordingly, soils are often treated as a three state system. Most soils have a density between 1 and 2 g/cm³. Soil is also known as earth: it is the substance from which our planet takes its name. Little of the soil composition of planet Earth is older than the Tertiary and most no older than the Pleistocene. In engineering, soil is referred to as regolith, or loose rock material.


Soil horizons

The naming of soil horizons is based on the type of material the horizons are composed of; these materials reflect the duration of the specific processes used in soil formation. They are labeled using a short hand notation of letters and numbers. They are described and classified by their color, size, texture, structure, consistency, root quantity, pH, voids, boundary characteristics, and if they have nodules or concretions.Any one soil profile does not have all the major horizons covered below; soils may have few or many horizons.
The exposure of parent material to favorable conditions produces initial soils that are suitable for plant growth. Plant growth often results in the accumulation of organic residues, the accumulated organic layer is called the O horizon. Biological organisms colonize and break down organic materials, making available nutrients that other plants and animals can live on. After sufficient time a distinctive organic surface layer forms with humus which is called the A horizon.

Typhoon

Typhoon formation
The typhoon origin, until now still was unable extremely todetermine, but known it is comes by the tropics atmosphere inperturbation development. On the tropics sea, the sea level because ofcauses the vertical incident solar rays the sea temperature toelevate, the sea water is easy to evaporate the water vapor to spreadin airborne, therefore on tropics sea air temperature high, humiditybig, this kind of air high inflates because of the temperature, causesthe density to reduce, the quality reduces, but nearby equator windpower weak, therefore is very easy to rise, has the convectioncurrent, simultaneously periphery the colder air inflow supplemented,then rises again, so moves in endless cycles, the end must entirecause  for the temperature higher, the weight to be all lighter,a density smaller air, this has formed so-called "the tropicaldepression". However flowing of the air is the proud barometricpressure flows to the low atmospheric pressure, looks like is thewater flows to the low spot from the high place to be same, all aroundthe barometric pressure compares the high place the air to have tocompare the low spot to the barometric pressure to flow, but forms"the wind". In summer, because the vertical incident solar rays regionmoves by the equator to the north, causes of southeast trade crossingthe line the southern hemisphere to change the southwest monsoon toinvade Northern Hemisphere, meets one another with the originalNorthern Hemisphere's Northeast Tradewind, compels crowds this airrise, the increase convection current, again because the southwestmonsoon and the Northeast Tradewind direction is different, meets oneanother often creates the undulation and the whirlpool. This kind ofsouthwest monsoon and the Northeast Tradewind meet one another thespoke which creates to gather the function, with the originalconvection current continuously, causes to form continues for the lowatmospheric pressure whirlpool to deepen, when is causes all aroundthe air speeds up to the whirlpool center class, the inflow quickly,its wind speed is bigger; When the near ground most gale fast arrivesor surpasses each second 17.2 meters, we called it is the typhoon.
Saw from the typhoon structure, the so giant colossus, it producesmust meet the unique requirement.

First, must have broad high temperature, the humidity atmosphere. Thetropics  on first floor atmosphere temperature and the humiditymainly decided to the sea level water temperature, the typhoon onlycan form Yu Haiwen is higher than 26 ℃ - 27 ℃ is warm  on,moreover in 60 meters depths sea water water temperatures all must behigher than 26 ℃ - 27 ℃;
Second, must have the lower atmosphere high level to gather, theinitial perturbation to the central spoke which proliferates tooutside. Moreover the high level spoke disperses must surpass theunderlying bed spoke to gather, can maintain the enough ascendantcurrent, the underlying bed perturbation can unceasingly strengthen;
Third, the vertical direction wind speed cannot differ too in a bigway, on the lower level air relative motion is very small, can causeto dive the heat energy centralism preservation which in the initialperturbation the water vapor congeals releases in  the area center, forms and strengthens the typhoon warm centerstructure
Fourth, must have the enough big place to transfer  thefunction, the earth rotation function is advantageous to the cyclonevortex production. Transfers  approaches nearby the equatorto zero, increases to the north and south two-pole, the typhoon occursprobably is leaving above the equator 5 latitudes  on.

Typhoon preventing and controlling

Strengthens the typhoon the monitor and the forecast, isreduces the typhoon disaster the important measure. Mainly uses themeteorological satellite to the typhoon survey. In the satellite cloudchart, can clearly see the typhoon the existence and the size. Usingthe meteorological satellite material, may determine the center of atyphoon the position, estimated the typhoon intensity, the monitortyphoon travel direction and the speed, as well as the violent stormappears the area and so on, to prevented and reduces the typhoondisaster to play the key role. When the typhoon arrives offshore, butalso may use the radar to monitor the typhoon movement. Also has themeteorological observatory , according to each kind ofmaterial which obtained arrives, analysis typhoon trend, lands theplace and the time, promptly issued the typhoon forecast, the typhoontight newspaper or the urgent alarm, through the television, mediumand so on broadcast serve for the public, simultaneously provides thepolicy-making basis for all levels of governments, issued the typhoonforecast or the tight newspaper are reduces the typhoon disaster theimportant measure.