The Warmer the Better
on Anthony Lovat in Bolgatanga (Ghana), 26/Mar/2011 12:05, 34 days ago
People who come from temperate countries assume a linear relationship between ambient temperature and enjoyment– cold is bad and unpleasant, warmth is good and enjoyable. “The warmer, the better”, we say. Long, dark winter months have trained us to believe this dogma.I mentioned on my facebook profile that it topped 48°C in the shade last week and was surprised by the replies. “Send some of that hot weather over here!” “Sounds lovely.” “Must be better than the cold and damp we’re having here at the moment.”We must maintain a constant core body temperature of 37°C to survive. If it rises above 42°C, a human being will die. To keep our core body temperature at this level, it is vital that our skin does not go above 35°C for more than a few hours. If it does, instead of heat being lost to the environment, the environment will be transferring heat into your body and this rapidly leads to serious overheating and death, even in the young and healthy.I complained about the heat to a number of people when we went back home over the particularly cold and snowy Christmas.“But it’s ok, isn’t it” they would say, “as long as it is a dry heat and you drink plenty of water.”Sweat evaporating from your body can carry latent heat energy away, thereby cooling the skin. We sweat continuously here– 24 hours a day. It saps your energy. You can’t stop thinking about it. Your clothes become drenched. Your skin becomes permanently flushed and covered in heat-rash, itchy red blotches across the entire body. You are still expected to work. You wake up in the morning to find the bed-sheets soaked in perspiration – looking as if you have poured a glass of water over where you slept.Dry conditions enable sweat to evaporate more easily from the body but without air movement, the humidity can be raised in your immediate surroundings to intolerable levels by the very evaporation of sweat you want to encourage. A ceiling fan is able to provide such air movement. It pushes the hot, dry air around you, dehydrating you so quickly that the water filter can barely keep pace with your thirst. It is still uncomfortable but is, at least, survivable. Far worse is when the electricity cuts out. It has been cutting out every Tuesday for the past six weeks and was out for four days last week across the whole Upper East Region. Without a fan, it is impossible to sleep. You lie in bed and can literally feel the perspiration pushing out of every pore. You sit outside in the shade during the day, longing for an elusive breeze.With the ability to combat heat-stress being a combination of temperature and humidity, a more useful measure of the environment is the“wet-bulb temperature”. This is the temperature recorded by an ordinary mercury thermometer wrapped in a wet cloth and shows the temperature you could theoretically lower your skin temperature to by sweating. Today is a cool day in Bolga – hence why I have the energy to write this. I have a mercury thermometer and it recorded a temperature of just over 40°C in the shade at 2:45pm. Having wrapped it in a damp cloth, the wet-bulb temperature reading is 29.5°C. Thankfully, the effect of evaporation is significant. A wet-bulb temperature of 35°C for longer than a few hours is lethal.To escape the cold of a northern winter is relatively easy– we can go inside and wrap up warm. If conditions get really cold, lighting a fire is a low cost solution.It is theoretically possible to escape the heat of the northern Ghanaian hot season. A tiny proportion of Bolga’s population is able to live in an air conditioned house or hotel, an air conditioned car and an air conditioned office. This is utterly out of reach to the majority. Even a ceiling fan is a luxury. Most people in Bolga are unable to escape the terrible effects of temperature. What must this do to the economy and to society? If it is 48°C in the shade, what temperature must this be in the sun, where many individuals are forced to work? Even at night, the dry-bulb temperature rarely drops below 30°C.With Laura being pregnant, the temperature has affected her terribly. Her‘morning sickness’ seems to be striking in the afternoon – coinciding with the worst of the heat. She lies naked under the fan, spraying her skin with water. She drinks icy water from the freezer. She can’t work. She can’t move.Due to meteorological phenomena, the maximum wet-bulb temperature possible on planet earth is currently 31°C, still 4°C within the limit of human survival. Anything higher than this and the hot, humid air will rise; leading to a thunderstorm will cool the environment down again like a natural thermostat.During a particularly hot and humid spell last week, we experienced just such a thunderstorm. The wet-bulb temperature must have been over 31°C. I had been in the regional office for most of the morning but, despite the ceiling fan, was suffering with the heat. I was on my way home for a shower (even the water flowing from the taps is hot – there’s no such thing as a cold shower) but stopped to see Donatus on the way. As I was talking with him, the sky darkened and the temperature plummeted. We could literally see the storm front travel towards us up the road. The wind hit first, kicking up a sea of dust. We scrambled for shelter but tin roofs were pulled from their houses and tossed around in the wind. We later heard that atleast two people died due to flying debris. Then it hailed. Yes – hailed. Giant blocks of ice as big as marbles hammered from the sky. Lightning crashed. It was the first hailstorm seen in Bolga for fifteen years. After twenty minutes the storm passed leaving a scene of devastation and a beautifully cool temperature. Donatus and I went to drink some pito. We sat on a log and soaked up the pleasant atmosphere. It was like the best English summer’s day. It was the first time either of us had not sweated for months.With global warming, the maximum wet-bulb temperature limit, the point before which a thunderstorm strikes, will creep upwards from its current 31°C frontier. Climate models predict that certain areas may experience wet-bulb temperatures of over 35°C and therefore become uninhabitable within 100 years. Bolgatanga is an area of the planet where, during the hot season around March, the wet-bulb temperature consistently reaches the maximum limit. Could it be that surviving a Bolga hot season may not be humanly possible in the future?The vast majority of the world’s population live in the tropics. “The warmer the better” is just another misconception we have developed in our temperate oasis of peace, wealth and comfort.