Frontier of scientific research: Scientists have found that forest fires will affect the formation of rain clouds in tropical rainforests.

A Brazilian study published in the journal Earth and Environment Communication shows how wildfires and agricultural forest burning affect the formation of rain clouds in the Amazon rainforest.

The authors say that aerosols (tiny solid particles and droplets discharged into the atmosphere by fire) will hinder the freezing of cloud droplets when the atmosphere is wet, but will also promote the freezing when the atmosphere is dry. This will change the natural function and typical height of clouds, and may also affect precipitation and the amount of sunlight reaching the ground.

In order to reach this conclusion, scientists used large-scale data sets collected from 2000 to 20 14 and 15, including satellite images of the National Oceanic and Atmospheric Administration (NOAA) of the United States, and the measurement results of atmospheric aerosols produced by the national aeronautics and space administration of the United States.

AERONET and reanalysis data of european centre for medium-range weather forecasts (ECMWF). ECMWF said that reanalysis data combined observations and past predictions with modern forecasting models, providing the most complete past weather and climate at present.

Satellite images and reanalysis data cover the entire Amazon region. Aerosol data cover five locations in southern Amazon: Alta Floresta and Cuyaba in Mato Grosso; Rio Blanco, Acre; Gibala and Oroporeto are both in London.

The purpose of this investigation is to observe and study the freezing temperature of water droplets in vertically formed convective clouds with a height exceeding 10 km, so as to determine the key driving factors of this phenomenon. The existence of ice in clouds is very important because it will affect the formation of rain and the average residence time of clouds in the atmosphere. Alexandre Correia, a professor of applied physics at the Institute of Physics (IF) of the University of S? o Paulo, said: "On average, the longer the cloud lasts, the more solar radiation will be reflected back into space, which will help the earth cool down." -USP) and the first author of the article.

This research was supported by FAPESP. * * * The authors are Irina Kaptelova Senna (Federal University of S? o Paulo), Maria Af Silva Diaz (IAG Institute of Astronomy, Geophysics and Atmospheric Sciences, University of the South Pacific) and Ilan Collen (Weizmann Institute of Science, Israel).

The results show that in this case, the icing does not occur at 0 C, but at-10 C, which mainly depends on the comprehensive effects of atmospheric humidification, solar radiation and aerosol. In the rainy season in southern Amazon (about 65438+February to April), the atmosphere is very clear, and the source of particles in aerosol is natural. They come from gas condensation from forests and wind erosion of soil and vegetation. They usually contain pollen, microorganisms and sea salt, as well as other kinds of particles. During the burning season from August to 10 every year, a large area of fire will release a lot of smoke, which will spread to the whole area and be blown to other areas by the wind. Correa said: "For example, compared with the urban activities in S? o Paulo, the pollution they produce is much more serious.

This research is a contribution to Amazon's knowledge of cloud behavior, which can be enriched through further research. "The impact of clouds on climate is very important. This is the most complicated topic in the climate model, and the purpose is to predict the future situation related to this topic. Therefore, any improvement in the knowledge of how the cloud works is a major issue and contributes to the progress of climate science, "he stressed.