What is ‘dirty rain’?

TAMPA, Fla. (WFLA) — “Dirty rain” is expected to fall in parts of Florida this week due to a huge plume of Saharan dust passing over the state, but what does this precipitation mean for the Tampa Bay area?

The Saharan Air Layer, commonly referred to as Saharan dust, is common this time of year . According to the National Oceanic and Atmospheric Administration , the plumes usually begin in mid-June and last until mid-August, with the dust peaking somewhere in the middle.

During concurrent tropical waves, the dust can become airborne and move west — impacting Florida. This week, the Sunshine State has seen an increased amount of dust particles in the area.

While Saharan dust is typically harmless, the plumes cause milky skies in the affected areas. However, it can also lower air quality in certain parts.

What is dirty rain?

Although the dust often aids rains and severe storms, helping Florida’s case during what’s projected to be a “ very active ” hurricane season, the fine dust particles become trapped inside water droplets, causing “dirty rain.”

“Dirty rain is when normal raindrops fall through tiny particles of dust or dirt. This time of the year, here in Tampa, we are prone to plumes of Saharan dust drifting across the Atlantic,” Max Defender 8 Meteorologist Rebecca Barry said.

“Lighter amounts of Saharan dust makes our sunrises and sunsets more vibrant, but heavier amounts can exacerbate respiratory issues. When rain droplets fall through these plumes of dust, some of the particles are absorbed by the raindrop, making the water in the raindrop ‘dirty,'” she added.

Even though “dirty rain” sounds scary, there is no harm associated with it — only a little mess.

“When these raindrops fall on the ground or objects, the dirtier drops can leave deposits of dust behind once they dry out,” Barry said. “In the springtime, sometimes we see a similar effect when it rains and the pollen levels are quite high.”

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