The vegetation effects in the production of microclimates in a urban tropical areas

THE VEGETATION EFFECTS IN THE PRODUCTION OF MICROCLIMATES IN A URBAN TROPICAL AREAS.

Gilda Tomasini Maitelli - Dep. of Geography/UFMT

Aluisio B. Borba Neto - Dep. of Agronomy/UFMT

Antonia Marília Nardes - Dep of Geography /UFMT

Neurozito Figueiredo Barbosa _ Dep. of Geography /UFMT

UFMT- Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil

E mail maitelli@zaz.com.br

The effects of the vegetation in the climate of a city have been important matter in several places of the world. In the continental tropical cities, where in general they happen the dry season (May-September) and a rainy one (October-April), with elevated temperatures the whole year and variations of humidity are significant , the maintenance of green areas is covered of great importance for the local climate. Being compared the microclimates produced by a surface vegetated with that found in a asphalted one it’s proven that the vegetation, through the evapotranspiration processes and interception of the solar radiation reduces the air temperature in the urban areas altering the conditions of relative humidity and can provides thermal comfort conditions .With the objective to prove such arguments and they were accomplished, during several days, of the day hourly measures of the air temperature and humidity using conventional and sensor psyichrometers installed in a thermal shelters and of surface temperature using infrared radiometers, in two places: a small forest with soil covered by grasses and trees whose cups touched each other and a parking , with soil covered with asphalt, located in the Campus of the Federal University of Mato Grosso, urban area of Cuiabá (15ºS and 56ºW), in the West Center Region of Brazil, They were selected a sunny day and one day with sun inserted with blows of rains (November/1999, rainy season), to compare the results of the research. The air temperature observed in the vegetated surface it was, on average 2.5ºC lower than in the parking reaching differences of even of 4.2ºC. The largest absolute air temperature values of the period were of 34.0ºC in the forest and of 38.2ºC in the parking. The surface covered with asphalt was always more heated up than the surface covered by gramineas and trees reaching the maximum difference of 38ºC in the hottest hours of the day. and at dusk the soil of the forest was 12ºC less warm than the parking. A relative humidity was, most of the time, 10% larger in the forest than the parking while the absolute humidity was similar in the two places. Other studies on microclimates produced in different areas in a city they can contribute to urban planning motivating the maintenance of green areas in the back yards and avenues as well as the one of forests that it can generate situations of more comfortable climate conditions.

Words key: microclimate, urbanization, green areas.