NO2 is the main source of nitrate aerosols, which form an important fraction of PM2.5 and, in the presence of ultraviolet light, of ozone.
二氧化氮是硝酸盐气溶胶的主要来源，构成PM 2.5和在紫外线下臭氧的主要部分。
2
In years past, spicules had been judged too cool to be a source of the high temperature plasma that, among other things, generates the sun's ultraviolet light.
过去，人们认为针状体的温度太低，除了产生太阳的紫外线，并不足以作为高温等离子体的发射源。
3
Harmful ultraviolet rays cause 90 percent of skin damage [source: Poirot].