【摘要】 在一定的太阳辐射条件下，地表湿润程度不同，蒸发速率也不同。当地表充分湿润时蒸发速率最快，地表温度也最低。利用热量收支平衡原理．这一最低温度可用一般气象观测资料计算得出，即称为平衡温度。于是气温与平衡温度的差值DT便可用作表示地表土壤含水量的指标，并且该指标可用于计算逐日或逐月蒸散发量、干湿气候区划、旱情监测、森林火灾预警以及用于预测灌溉所引起的气温变化等方面。更多还原

【Abstract】 If the solar radiation is constant, the soil humidity of the earth, s surface is larger, and the evaporativity is greater. The maximum rate of evapotranspiration occurss from an earth’s surface with adequate moisture, while the surf act temperature is lowest. The lowest temperature can be calculated by using ordinary meteorological data according to the principle of heat balance which is called equilibrium temperature. By subtracting the equilibrium temperature from air temperature, a new value DT is obtained, which can be used in the following aspects: to indicate the soil humidity of a large area on the earth’s surface; to calculate the monthly and daily evapotranspiration; to clefferntiate dry and humid climates; to supervise drought disastes; to warn forest fire and to predict the temperature changes caused by irrigation.更多还原