Temperatura: temperatura média diária do ar (notícia explicativa)

Summary

The air temperature is one of the most important climatological ele- ments. To give a representative reading of the air temperature, thermome- ters should be protected from radiation, from the sun, sky, earth and any surrounding objects, but at the same time be adequately ventilated. One of the methods of protection now in general use is the louvered thermometer screen. By international agreement, the air temperature is measured with ther- mometers at a height of between 1.25 and 2 meters above ground level, insi- de a louvered thermometer screen. The so measured temperature is said to be the surface air temperature. The range of the diurnal variation of the air temperature varies with the season and the local conditions; its value is one of the most significant cli- matological indexes. There are different ranges in the variation of the surface air temperatu- re: the daily, the monthly and the annual variations. The average value of the air temperature during a day is the average temperature of the day. This average value is calculated by different tempe- rature methods. The more common one is the quotient by two of the sum of maximum and minimum temperatures of the day. The air temperature decreases with the altitude, as a rule, in the tro- posphere or lower laver of the atmosphere. The rate of the vertical variation 6