Atmospheric residence time is the average time spent by a molecule in the atmosphere, after it leaves a source and before it encounters a sink. The tracking models estimate the global average residence time to be around 8.5 days based on Eka-interium data, thus according to recent study the average residence time of water in the atmosphere is 4−5 day's is not correct. It is around 8.5. Methane has lowest average atmospheric residence time among the greenhouse gases.