Vapor is responsible for the familiar processes of cloud formation and condensation. Early forms of distillation involved batch processes using one vaporization and one condensation. Fog and clouds form through condensation around cloud condensation nuclei. The material sets by a condensation polymerisation reaction. Nylon 66 is a material manufactured by condensation polymerization. Reports of frostbite, condensation, and other temperature changes can occur. These imines can be used to direct subsequent reactions like an aldol condensation. Capacitive sensors are robust against effects such as condensation and temporary high temperatures. Hydrogen is an extreme example of this form of condensation. It is a modification of the aldol condensation. Enones are typically produced using an aldol condensation or Knoevenagel condensation. Ethyl 2-methylacetoacetate and campholenic aldehyde react in an Aldol condensation. This results in the formation of a visible funnel cloud or condensation funnel. These products arise via an initial aldol condensation to give diacetone alcohol. Supersaturation occurs in the absence of condensation nuclei.