Ooooh that smell. Can’t you smell that smell? That might have gotten the attention of Lynyrd Skynyrd fans, or sound familiar for another reason. This was the start of an article I posted on June 5 with a similar set up to what we have this week near the Chesapeake Bay.  Back in June it was a funky oder in Anne Arundel County today was unavoidable.  A low level haze with a chemical smell led to numerous calls to local fire departments between Pasadena and Glen Burnie.  Something similar happened earlier this week in Cecil County. It was caused by something called an inversion, a phenomenon that often occurs overnight or with long duration clam weather. The morning fog and lingering haze is an example that it has been hanging around all week long. In essence you can blame the same bubble protecting us from storms for trapping the air and pollution in place.

What is an ‘Inversion’?

Inversion and pollution build upUnder normal conditions during the day, the sun warms the ground. This in turn warms the low level air which rises and eventually cools. This ‘lapse rate’ under dry conditions will cool at about 5 degrees per 1000 feet.  When an unseasonal warm up contrasts with cooling near the Chesapeake Bay and Atlantic Ocean, the air locally can cool, remain damp, and stay close to the ground. Meanwhile inland, the air warms and can rise just above the shoreline air. When the air is warmer above that ground than the surface, that is called an inversion. This can prevent normal mixing and allow particles and pollution to build up.

An inversion is most common in calm weather, early in the morning.  Also, in valleys between surrounding hills or mountains.  The ground has a chance to cool all night as warmer air rises making the hill tops warmer, and a layer of air in between. This can help fog to form or linger longer when there enough moisture present.

Is it safe to go outside?

pollution air quality forecastThe smell was determined to be non-toxic, but try convincing those that were caught in the brown cloud and haze. Pee-yew!  It was likely a concoction of pollution from cars, trucks, and industry. But if you are sensitive to breathing issues, this will be noticeable.

The Air Quality Index is an average of 24 hours and set limits by the EPA. It is already running on the high end in southern Pennsylvania today. With near record heat this weekend along with light winds, haze, particles, and pollution build up could become an issue near urban areas again. Perhaps near or downwind of Baltimore. Even a slight breeze can keep the air trapped, but slosh the ‘brown cloud’ around.

Good luck getting out to enjoy temps (away from the water) approaching 70F by Sunday.


Faith In The Flakes: It Will Snow… Eventually

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Chip KidWxDevicesGet the award winning Kid Weather App I made with my oldest son and support our love for science, weather, and technology. Our 3 year anniversary of the release and our contribution to STEM education is this November. It has been downloaded in 60 countries, and works in both temperature scales. With your support we can expand on the fun introduction to science and real weather.[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]