An analysis of data from the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite indicates that there is a wet layer about 70 to 80 km up. It is generally believed that water vapour in the atmosphere is trapped below 12 km while the region between 50 and 90 km (the mesosphere) is almost dry. According to Louis Frank at the University of Iowa, USA, small comets that encroach upon the outer reaches of the atmosphere, release water continuously that ends up in the mesosphere (Science , Vol 277, NO 5329).
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.