If the poreis completely closed to the surface, the result is a whitehead. If the pore is wide open, oil becomes oxidized (that is, acted on by oxygen in the air), the oil changes from white to black, and the result is a blackhead. This is how the two types of comedones develop. Comedo is the Latin word for glutton.
The Amazon rainforest topical climate. Tropical climate refers to zones in a range of latitudes between 5/10 to 35. The temperatures remain high all over the year and shows an annual wide change in precipitations with wet and dry seasons: The dry season duration is proportional to the latitude to ultimatly become a mostly dry area.
(Sources (FAO). The tropical steppe climate is a transitional climate between the tropical wet and tropical dry climates. The controlling factors of the climate are similar to that of the tropical dry climate, though temperatures are cooler and annual precipitation is higher.he tropical steppe is not as dry as the tropical desert climate as it lies closer to a source of moisture. If on the equatorward side of the desert it is the ITCZ, or the subpolar low and midlatitude cyclones if it is located poleward side.