An air mass indicator, to register prevailing weather conditions in terms of temperature and humidity. designed by Athelstan F. Spilhaus of the Massachusetts Institute of Technology. It does not forecast weather but records for the layman the varying weather conditions he is accustomed to describe as "scorching", "muggy", "raw", "keen", "damp", "dry" or "frosty". For the scientist it identifies the particular type of air mass overlying a region. It is expected to be useful in aviation to warn pilots of the conditions that cause ice to form on airplane wings and is also expected to be used in air-conditioned buildings for indicating comfortable conditions