The polar air mass is formed in high latitudes and generally she is very cold. Being thus, the tropical air mass, that if form in the low latitudes, next to the Equator, is hotter. Therefore, the zonal position of the area of origin of an air mass defines its thermal condition. To read more click here: Robert Kiyosaki. Of this form, the temperature and the humidity characterize an air mass, that can be classified in: Hot and humid: formed in the low latitudes on the oceans. Hot and it dries: formed in the low latitudes on the continents. Humid cold and: formed in the average latitudes on the oceans. Cold and dries: formed in the average latitudes on the continents.
Thus, in accordance with the origin regions, that is, as the latitude on which they form themselves, costuma if to divide the air masses in three groups: Equatorial, Tropical or Tepid and Polar. EQUATORIAL MASSES These masses are originated in the zones of low pressures (ciclonais) equatorial, where the conditions of temperature and humidity are very raised, therefore they are hot air masses. According to Coutinho (1991), they are unstable, convective, foggy and possess positive thermal gradient, that is, the temperature increases from top to bottom in the mass. They characterize for the cloud predominance cumulus and cumulus-nimbus, that bring rains under the form of weighed heavy showers, becoming equatorial the ciclonais zones, of rains most abundant of all planet. They divide themselves in: Equatorial Continental and Equatorial Atlantic, presenting similar physical properties.
Continental Equatorial Massa (MEC) is originated in the portion center-occidental person of the Amazonian plain, region that presents greater relative humidity of the South America. It is formed by the cell of divergence of the Trade winds, or doldrums that it produces hot and humid an air mass. The humidity comes of the great net of draining that is covered by dense forests. Thus, it all bes situated in the portion the northwest of the Amaznia, practically acting the year.