Environmental diffusion

当一种可能是恶臭的、易燃的或有毒的气体被释放到大气边界层时，人们想知道在不同地点和时间可能遇到的浓度值。这些浓度值很难预测或测量。环境处于动荡状态，在现场（以及实验室）测量中记录的非常不规则的浓度值通常表现出浓度的极端偏差，这是名义平均水平的许多倍。通常用于浓度值量化的描述符是概率密度函数，但这在环境背景下是不切实际的。

When a gas, which may be malodorous, flammable or toxic, is released into the atmospheric boundary-layer one would like to know the probable concentration values encountered at various locations and times. These concentration values are very difficult to predict or to measure.The environment is in a turbulent state and the very irregular values of concentration recorded in field (and also in laboratory) measurements commonly exhibit extreme excursions of concentration that are many times the nominal average level. The usual descriptor used for the quantification of concentration values is the probability density function however this is impractical in the environmental context.