Residents in the St. Louis area woke up to dust and particles covering their cars. While some thought it was pollen, others were just confused by what caused the spots.
Turns out, it was "dirty rain."
"Dirty” or “muddy” rain is just what it sounds like, rain that has dirt or dust particles in it. Dust can become suspended in the atmosphere and attach itself to water droplets. As these water droplets rain out from the cloud, the water and combined dust/dirt fall out with it.
It might not be noticeable on a surface that already contains dust or dirt on it, but the hood of a recently washed car would certainly show it.
Areas along the desert southwest saw windy conditions on Thursday. Thanks to drought conditions, the dust from this region was lifted into the air, creating low visibilities. Parts of Interstate-10 were shut down in Las Cruces, N.M. because of poor visibilities from the blowing dust.
The particles were blown into the middle part of the country where they combined with the light rain we experienced this morning, thus producing the “dirty” or “muddy” rain.
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