Editing Smoke screen (section)

===Phosphorus===
{{Main|White phosphorus (weapon)}}
Red [[phosphorus]] and [[white phosphorus incendiary|white phosphorus]] (WP) are red or waxy yellow or white substances. White phosphorus is [[Pyrophoricity|pyrophoric]] - can be handled safely when under water, but in contact with air it spontaneously ignites. It is used as an [[Incendiary device|incendiary]]. Both types of phosphorus are used for smoke generation, mostly in artillery shells, bombs, and grenades. <!-- effects of exposure? -->

White phosphorus smoke is typically very hot and may cause burns on contact. Red phosphorus is less reactive, does not ignite spontaneously, and its smoke does not cause thermal burns - for this reason it is safer to handle, but cannot be used so easily as an incendiary.

Aerosol of burning phosphorus particles is an effective obscurant against [[thermal imaging]] systems. However, this effect is short-lived. After the phosphorus particles fully burn, the smoke reverts from emission to absorption. While very effective in the visible spectrum, cool phosphorus smoke has only low absorption and scattering in infrared wavelengths. Additives in the smoke that involve this part of the spectrum may be visible to thermal imagers or IR viewers.<ref name="yarchive.net">{{cite web|url=http://yarchive.net/mil/infrared_smoke.html|title=Infrared smoke (Arno Hahma)|website=yarchive.net}}</ref>