The book “Follow the sun” shows that hours of daylight, temperature and relative humidity which all can be gotten from free public sources are the main drivers of covid-19 transmission . In the spring, the decline of cases from peak is almost entirely dominated by daylight hours – or to be more precise, daylight seconds! Here is a simple little app that you can have fun with and check against the real numbers for that day – again available free on the web!
For Ireland we established this formula where Y is number of transmissions and X is number of daylight seconds
Y = exp(a + b*X), with a = 25,8428 and b = -0,000375156.
Y = exp(a + b*X), with a = 25,9625 and b = -0,000368539.
These look daunting but we're going to show you how to use them in 2
minutes! First of all, you look up the daylight hours in Dublin and Madrid using these tables;
Remember Madrid has shorter days than Dublin in summer. Now convert this to seconds by multiplying by 3600. For example, 14 hours is almost exactly daylight in Madrid on May 2 and 14*3600 is 50400.
So we put this in the formula above and get exp( 25.9625-(0.000368539*50400))
Here is the really cool part. You can simply copy and paste this into the following free online resource and press return;
You get 1,616.7 and the real value is 1781 so this is not bad and certainly better than what the state scientists were predicting.
The longest day in Ireland is almost exactly 17 hours or 61,200 seconds long and we put in to get
exp(25.8428 -0.000375156*61200) which as you can verify is 17.872 which again is closer than the prediction of the state “SIR” model.
We invite you to check that for Ireland on May 25, we get the bullseye – both the model and real data give 59!
Please note the real data is what we call “noisy” with bias due to labs closed on weekends, late reports of tests and so on.
Nevertheless, you will find our model works really well from peak which was 20 March in Spain and 16 April in Ireland until the end of June After that, temperature and humidity become more important in ways the book explains as it sets out a model that works for transmission anywhere in the world, anytime.