Genesis of convective clouds - Anvil and tropopause
The air close to the surface as a result of solar heating expands and its density decreases making it up in the form of thermal and air are mixed through which rise. The level of condensation is determined from an average of moisture along the vertical. As a result of mixing the clouds condense at the same height over large areas and have a flat base. The first clouds which are formed for this phenomenon are the "cumulus" and their top rising appears as in boiling with the appearance of a cauliflower with the contours very well defined. Unlike the gradually rising in the air dilutes the smoke a cumulus appears suddenly, gradually diluted, but it disappears just as suddenly when the droplets evaporate it up. The air between the clouds contains less steam would otherwise be occupied by clouds of course also: as a consequence of the cumulus are subjected to continuous evaporation over their entire lateral surface. The cloud grows at the top because the air inside goes up, pushing towards the outside. In due course the thermal exhaust their impetus and the evaporation takes over. The cumulus carrying heat (due to their temperature in excess) and humidity upwards. However, in their upper part, the evaporation can use more heat than the heat transported upward and the air is cool, even if some time after the heat used to evaporate the cloud may appear again if a new cloud is formed by the ascent at higher levels. When the clouds reach even higher levels of the tops become colder until at some point the droplets freeze and become ice crystals. We call this process freezing (glaciation), which is the same as freezing (freezing), apart from the fact that does not occur until the temperature falls well below 0 ° C. The icing still releases some latent heat of which 1/6 is released by condensation around. This however is not the major effect that has on the icing cloud. The ice evaporates less easily the droplets of liquid water and so the ice crystals grow while the water droplets evaporate if both are present in the air mass. Thus the particles of ice become enlarged and it is easier that has fallen (fallout). In addition, the air can be saturated with respect to ice and not to water so that the cloud, freezing, may cease to evaporate, which makes it possible to further growth, and this could not happen without the icing.
Anvil and the tropopause
If there is a stable layer (inversion) at a certain level that the heat does not have sufficient strength to penetrate, the latter are flattened towards the outside and open horizontally as if encounter a sort of "ceiling". The shape of the cloud approximates that of an anvil (anvil), and so it is called. When the cumulus are restricted because of an inversion layer, they become flattened and are defined stratocumulus (stratocumulus). If the layer of flattening has a horizontal base clearly identifiable well above the base of the cumulus, then the original is defined anvil stratocumulus. This leads us to wonder how high it can climb the tallest of the mounds. There have to be a limit as the temperature falls with the share in the region where the convective cloud grows and the vertical gradient increases from 4 ° C km-1 typically at the base of the cloud to 9 ° C km-1 to 300 hPa (10 km) and obviously could not fall, even theoretically, below absolute zero (-273 ° C), which would happen around 35 km above the ground. The air would reach a radiative equilibrium temperature of about -50 ° C as a result of being heated from below and losing heat from Earth to outer space. This temperature is more or less the same depth of several km from about 12 to 30 miles and the air between these levels is very stable because the vertical gradient is almost zero. This layer of atmosphere called the stratosphere because it is stable stratified layers. The air below is called the troposphere, which means mixed region and the mixing is the result of all the other convective clouds and storm clouds. The boundary between the troposphere and stratosphere is called the tropopause. Normally, the anvils have begun the icing well below the tropopause so that have an appearance silky and are described as anvils of ice to contrast with the stratocumuls anvils which are not usually frozen. The tropopause is between 14 and 18 km above sea level in the tropics and larger clouds can penetrate up to above 3 or 4 km. For most of the penetration is around 1 km. In middle latitudes there are places where the tropopause is lowered below the normal decrease from the tropics to the poles: this happens at the edges where the air comes from different geographical locations on both sides. The tropopause is often "folded" on itself on the sides and produces a double or triple tropopause. Here is where the majority of exchanges air with the stratosphere and it may take one or two days before the primary radiation balance is restored in the meantime there may be two or three inversions in the lower stratosphere. Due to the high stability of the stratosphere air navigation is easier than in the turbulent atmosphere. The clear air between the heaps is also stable and is easier to fly through it that inside the cloud or below of its base where the thermal dried make the flights very jolting. When they produce rain accumulations become, in theory at least, of cumulonimbus clouds (cumulonimbus) name that literally tells you heaps precipitants. The name, however, is reserved for clouds organized to produce showers (showers) of long duration and this normally requires anvils frozen.