Terrestrial Accretion from the Solar Wind

Abstract

C. M. DE TURVILLE1 has suggested that most of the water now present on Earth has been formed, from hydrogen in the solar wind, in combination with oxygen in the Earth's atmosphere. If this is so, then the process must still be going on, forming water vapour, according to de Turville, at a rate of about 2 × 10−12 gm. cm.−2 sec.−1. The water is presumably being formed at very high levels (above 100 km.) where oxygen in the atomic form exists. The continuous formation of water vapour at these levels must lead to a gradient of the water vapour mixing ratio (the ratio of the mass of water vapour to the mass of air) decreasing downwards until overtaken by the gradient decreasing upwards arising from evaporation of water from the surface of the Earth. What measurements there are do suggest such gradients2, and it is interesting to consider whether the humidities found could conceivably arise inthis way.