Thermal inversion and pollution
Wednesday, 13 June 2007, Written by Julien   
The last few days were really bad in Beijing, with grey sky and heavy smog. It is mainly due to thermal inversion.

You might have heard of convection. This is a natural phenomena that creates circulation in fluids from temperature differences. It is convection that creates bubbling when heating water. It happens because cold water is heavier than warm water.

Convection


Normally speaking, the same thing happens in the atmosphere, and the air heated by the ground tends to be replaced by fresh air from above. That is great to clean polluted air.

However, in some cases, air in altitude is warmer than air on the ground, so the convection cannot occur. Air stays and pollution accumulates! That's what happened those last days.

Today, the wind is back, so pollution has been taken away, air is fresher and the smog is partly gone!

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Comments
Camillenchine wrote :
I confess, I don't read your blog everyday. And I really don't know why because each time I read it, I learn something useful and I feel less ignorant! Thank you for lightning my smoky brain on scientific problems I never thought I could understand one day ... I was such a useless one at school in scientific classes!
Dalton wrote : Thank you
Well im in school and they didnt really explain it well... this helped me alot Thanks
chammie wrote :
thanks! this really helped me a lot.
Nirmal Chauhan wrote : Thermal Inversion
Thermal inversion occurs when a layer of warm air settles over a layer of cooler air that lies near the ground. The warm air holds down the cool air and prevents pollutants from rising and scattering.
Nirmal Chauhan wrote : Thermal inversion
Thermal inversion occurs when a layer of warm air settles over a layer of cooler air that lies near the ground. The warm air holds down the cool air and prevents pollutants from rising and scattering.
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