The forecast for today in Tel Aviv is a balmy 29 to 31 degrees Celsius, depending on who you ask, and for Jerusalem it's 35 or 36 degrees. But leave the embrace of your air conditioner and you'll be soaked in sweat before walking ten feet, because of heat stress, which is particularly onerous today – "heavy to extreme", the Israel Meterological Service warns.
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Heat stress, or the "heat index," is a mathematical calculation that represents not the ambient temperature, but our perception of the ambient temperature. What it means is that today is very hot and also very humid. Israel Radio went so far as to sum up the forecast in a word: "Unbearable."
People and other animals sweat to cool their bodies on hot days. But when humidity is heavy, it prevents our sweat from evaporating into the air and cooling us. If we don't take precautions, the result can be heat-related illnesses, from mild cramps (which is your body begging for salt and electrolytes to replace those lost in sweat) to heat prostration and finally, heat stroke, which can be deadly.
Symptoms of heat prostration (or exhaustion) can include fatigue, headache, nausea, and the shakes, and loss of appetite; and as our water and salt loss advance, we may suffer anxiety and impaired judgment.
What can you do about this? You could stay inside, and if you go out, make sure to stay hydrated, drinking a lot of water or other non-alcoholic fluid, avoid heavy exertion and preferably stick to light meals. If you're feeling poorly, rest in the shade and drink.
The stress, not the temperature in and of itself, is the real problem of the "heat dome" that has been baking the Middle East, particularly Iraq and Iran, this last month.
Meteorologists measure temperature of the air using thermometers inside shaded weather station huts with slatted walls, through which the wind can freely flow, but sunlight cannot penetrate. The huts are painted white lest they absorb excess heat that could distort the thermometer reading.
Thus, for instance, the ambient temperature measured in Bandar-e Mahshahr, Iran last week was "just" 46 degrees Celsius, but the heat stress created a feeling that it was 74 degrees. Which it wasn't. It just felt that way.
And for today, the forecast for Bandar-e Mahshahr is 95 degrees F (35 degrees C), which will feel like 123 degrees.
Is this "heat dome" because of climate change? Almost no scientist will categorically say yes, because specific weather phenomena could be part of normal, local fluctuation. But almost all scientists will categorically say that climate change and global warming are happening, and happening fast, and the Middle East is expected to become hotter and (for all the humidity) - drier. That forecast at least seems to be right on the nose.