Is there any effect of weather on the spread of Covid-19?

Weather reports:

Average pressure in Wuhan in December 2019 was 1026 mbar, with some days going as high as 1040 mbar. Wind was very low too – 1-5mph. Dry.

Average pressure in Milan in January 2020 was 1027 mbar, with some days as high as 1045 mbar. Wind was very low – 1-3 mph, mostly dry

For comparison

Average pressure in Newcastle upon Tyne in February 2020 was 999 mbar, Wind was typically very strong – more than 20mph, lot of rain.

Molecular and cellular transmission:

What is the relative permittivity of air for odours and viruses? How does it depend on the weather?

Have you every walked behind a person having a lot of perfume? On a windy and rainy day, with low pressure you’d hardly feel any smell. But on a dry, sunny day, with high pressure, the scent of perfume stays so long that you can feel it even if the lady is 100-200 meters ahead of you, or even long past.

What is smell? What is its nature? In science it is explained via special types of molecules, called odorants.

With Covid-19, we have been told that we should keep the distance of 2m in social distancing. Is it enough? In what weather?

The Covid-19 cells are very small. Apparently the size of 100 nanometers. So we are talking about something like 1000 molecules. On a high pressure, dry and non-windy day, they can stay in the air probably for quite a while.

The other factor of good and dry weather is that people are much more out and about, and naturally socialise more. So, the weather and social proximity are correlated too.

Extra point. On a low pressure day our body naturally extract more fluid, mucus etc. This is actually good to help not letting virus into your body. On the contrary on a high pressure sunny day we are naturally keeping everything inside and actively breath oxygen rich air. Especially if we exercise outdoors. Perhaps, virus likes that we help it with extra oxygen and give its way into our lungs when we exercise. So is active exercising is good during those days and in a social company of potentially viral people. I am not sure.

We are often mistaken that by doing something normally good we can win. Unfortunately, there is no universal win. What’s good for your body under normal conditions may be bad under these viral conditions. Good old saying, you can’t win, man, can you!?

My hypothesis is that a good weather is really a ‘good’ promoter for viral transmission.

2 thoughts on “Is there any effect of weather on the spread of Covid-19?

  1. Good observations. On the day when they published the “close contact = 2 metres and 15 minutes” rule, I was waiting to cross a street. Four lanes so at least 10 metres across. Another person was waiting the same light at the opposite side. They rolled a smoke, lit it, inhaled then exhaled. In a few seconds I was smelling cannabis. Subsequently walking past the person in the middle of the street confirmed that was what they were smoking. Nobody else within 50 metres of either of us. Sunny, no appreciable wind, not too sure what the air pressure was. But within 10 seconds I was breathing in air that had been breathed out by someone from over 10 metres away. So should the rule really be the 10/10 rule: 10 seconds at 10 metres?

    This is of course pessimistic. Hopefully you need to get some quantity of virus into your system at once to be infected, i.e. some epsilon amount. Less than that you might gradually develop some sort of antibody without a full blown infection. That’s why not protecting the medics properly is insane.

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