Abstract
It was aimed evaluate the variations of monthly average of global radiation and frequencies of global atmospheric transmissivity coefficient (Kt) in 16 municipalities of amazonic region of Mato Grosso State. The data used were obtained by the National Institute of Meteorology, in period between 2008 and 2014. The Kt was obtained by the ratio between global radiation and radiation incident on the top of the atmosphere. It was adopted the sky coverage classification in Kt function for daily partition into four classes: I - cloudy sky (Kt ≤ 0.35), II - partially cloudy sky (0.35 ≤ Kt ≥ 0.55), III - partially open sky (0.55 ≤ Kt ≥ 0.65) and IV - open sky (Kt > 0.65). Between April to September (dry season) occurs higher indexes of atmospheric transmissivity due to the low attenuation of solar radiation by interaction with atmospheric constituents, with higher frequencies of sky condition IV and II. The sky coverage conditions are dependent on regional rainfall behavior and show differentiated average percentage between the municipalities in the amazonic biome.
Keywords:
atmospheric absorption; climatic conditions; clearness index; nebulosity
