When melting snow-crystals or raindrops fall through very cold air, they freeze to form small particles of ice, called sleet.

VOA: special.2011.01.11

These extremely small particles are believed to be linked to comets.

VOA: special.2009.01.20

These can be sulfate,nitrate, ammonia,sodium chloride and if these are small particles they can be dangerous because if they are inhaled they can reach the lungs."

VOA: standard.2010.04.16

I can see footprints of my boots in the small,fine particles.

VOA: special.2009.07.15

If dark matter particles exist, scientists say, they should be able to observe a small amount of light given off when they hit the nucleus of a xenon atom.

VOA: special.2009.07.21