Aerological evidence of large‐scale mixing in the atmosphere

As a result of the general acceptance of air‐mass analysis by American meteorologists, the number of aerological stations in the United States has been increased to such an extent that it is now frequently possible to prepare daily synoptic charts, not only for the sea‐level but also for selected levels in the lower half of the troposphere. At present, this aerological material is being utilized primarily for the purpose of verifying the surface‐map analyses, minor exceptions being the use of thermodynamic diagrams in the forecasting of thunder‐storms and of ice‐formation on aircraft. Our experience during the last few years indicates that two practically identical surfacemaps may be associated with widely different vertical structures; it should therefore be possibleto extract from the upper‐air data information not implicitly contained in the surface‐reports. Our present inability to do so is probably the result of unsatisfactory methods of representing t:ie state of the free atmosphere. The purpose of this preliminary report is to discuss briefly certain, studies now in progress at the Massachusetts Institute of Technology, which have as one of their aims the development of improved methods for the treatment of aerological data.