Having returned from a fortnight’s break, I wonder if we get holidays all wrong. In northern Europe, the custom is that you head south to spend time on the beach. But equally, there is such a thing as too damned hot, especially if, like me, you have a healthy dose of Celtic ancestry.
To avoid this, you need to study what is called the ‘wet-bulb temperature’. This is a measure of temperature which accounts for the cooling effect of evaporation. At 100 per cent relative humidity, the wet-bulb temperature is equal to the dry-bulb temperature shown on weather forecasts. At lower humidity the wet-bulb temperature is lower, owing to evaporative cooling, a mechanism all humans other than Prince Andrew depend on to reduce their body temperature. This explains why I can wander around Phoenix comfortably at 100°F, while I find London at 90° uninhabitable.
It’s the wet-bulb component of temperature that environmentalists should be eager to warn us about. Above a wet-bulb temperature of 90°, even a fit, well-hydrated human sitting by a fan cannot really function. Add a few degrees and they die. We should consider humidity before deciding where to go on holiday. But we don’t.
Another reason not to head south next summer is something we barely think about at all: hours of daylight. True, southerly climes are warmer – but it’s dark after dinner. There’s virtually no twilight, even in southern France, and you’re left in darkness with the din of mopeds and barking dogs. By contrast, go to Scandinavia or Scotland in June or July and it will probably rain a bit, but with 18+ hours of daylight to play with, who cares?
My final holiday tip is to avoid uber-famous cities, which are overcrowded and expensive at peak times.