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.
The Tropical Wet/Dry climate lies at latitudes of about 5o - 10o and 15o - 20o. Broad expanses of the savanna exist in north and south central Africa, The Llanos of Venezuela, Campos of Brazil, much of northern and eastern India, western Central America, the Caribbean Islands, and south Florida, Myanmar (Burma) and the Indo-Chinese Peninsula.