Can flames burn at low temperatures?

The temperature to which a material must be heated before it catches fire in atmospheric air is known as the ignition temperature. It varies from material to material, and a group of materials – pyrophoric substances – selfignite at less than room temperature, as soon as they make contact with air.

Triethylborane will selfignite at temperatures far below the freezing point and starts to burn with a green flame. A low ignition temperature does not mean that the flames are not hot, but under very special circumstances, some organic fuels such as diesel can burn with "cold" flames that are less than 400 degrees hot. Scientists still do not know very much about the phenomenon.

Triethylborane self-ignites, when it makes contact with the air even at temperatures below zero. It is used to ignite jet and rocket engines.