Wednesday, 29 April 2009

Weather and Flu

I was talking on the radio this week about relationships between weather and flu and it occurred to me with all our advances in medical sciences there is still a lot we don’t know about things that are common to us, like the flu virus.

That’s not to do down the virologists as we know a lot of technical information about the virus and that it has different strains (this swine flu appears to be from the H1 N1 strain) and how viruses generally transmit across large populations thanks to some clever epidemiological studies - that by the way use the same mathematics that model the spread of new technologies, like the iPod, across populations. However we don’t really know how viruses interact with the environment in detail.

Take the weather for example. We know flu peaks in the winter months in Europe (between December and March in the northern hemisphere to be a bit more precise), but what we don’t know is whether that is due to changes in things like temperature and the UV in sunlight directly, or simply that it’s how people respond to these changing weather conditions that help transmission. For example, people tend to congregate indoors more in the winter months, where a greater number of people are in closer proximity and often humidity is higher (which perhaps helps the virus survive).

Almost certainly humidity is a factor in virus lifetime and transmission. We can see that in the tropics the flu cycle is much extended beyond the winter months, in large part because of the humidity.

After all that technical detail, the best defence we have is to wash our hands. How often does solving a difficult problem come back to basics!

Friday, 24 April 2009

Living in Different Climates

I’m recently back from Miami and a tour of some of the Caribbean islands on holiday. Great holiday and my first time to the Caribbean. Travelling south in the Caribbean Sea it occurred to me that I wouldn’t want to live in a tropical climate. I would miss the seasons. They do have changes in the weather – very hot, or very wet and very hot! It’s nice for a holiday, but it wouldn’t be for me as a way of life. I like the variability that our seasons bring - even, like this week, when I get wet through walking into the office.

We adapt to our weather pretty well in the UK, except for the occasional snow flurry, but it doesn’t really impact on our way of life in a big way! I’ve seen written that weather has a £2 – 3 billion impact on our economy each year on average, and individual events can have equally large and comparable financial and social impacts.

Businesses can now buy a wide range of services to lessen the impacts of weather on their performance (it’s no longer a feasible excuse for a business to use to their shareholders for poor performance). The Public Weather Service provides the variety of weather warnings we see on the web, TV and hear on radio that helps us manage our own lives. But that’s certainly not as simple in some countries who suffer the impacts of significant and severe weather on a regular basis. It does genuinely affect the way people live their lives and I think, interestingly, the way in which those countries will choose to move forward in their own growth and development that will certainly be founded in very different cultural (weather-driven) roots.

Now I need to balance out my reflections with something a little less philosophical so here is the temperature profiles for my flights as my regular blog readers have come to expect of me. These show my descents out of Amsterdam at 1237 UTC on 11 April (as I flew via here) and then into Miami at 2300 GMT on the same day.

You can see from the plot that although much later in the day, the atmosphere is quite a bit warmer all the way through the troposphere. The zero degrees C isotherm was almost 2 km higher in Miami in the late evening than it was in Amsterdam around midday. You can probably also tell from the profiles that it was a pretty smooth take-off and landing.

My hope is that you’ll be encouraged to collect the same information when you next take a flight and send it to the blog.