The standard presents types of open-air climate in terms of temperature and humidity. Intended to be used as a part of the background material when selecting appropriate temperature and humidity severities for product applications.
DS/IEC 721-2-1+Amd.1:1990 history
1990DS/IEC 721-2-1+Amd.1:1990 Classification of evironmental conditions - Part 2: Environmental conditions appearing in nature - Temperature and humidity
1990DS/IEC 721-2-1:1990 Classification of environmental conditions. Part 2: Environmental conditions appearing in nature. Temperature and humidity.