Are you feeling very humid right now? That's just the beginning

2024-07-24 2024-07-24T14:23:23Z

Weather of Arabia - The Arab world is currently going through a severe heat wave that subsides slightly, then rises again, and is accompanied by intense humidity that increases the feeling of heat to unprecedented levels in some Arab cities.

July and August witness the peak of summer in the region, and as temperatures rise, the rate of evaporation from bodies of water, soil, and vegetation increases, leading to increased humidity levels.

Evaporation and humidity

Many Arab countries are located near large bodies of water such as the Arabian Gulf, the Red Sea, the Arabian Sea, and the Mediterranean Sea. The evaporation of water from these warm seas in the summer heat increases the humidity in the air, and the coastal areas are most affected by this marine influence, as the winds coming from the sea carry more moisture inland.

Temperatures rise in the summer, creating low-pressure systems that pull moist air from the surrounding seas. In addition, warm air can hold more water vapor than cold air, according to the Clausius-Claybron equation, which states that the ability of air to retain moisture approximately doubles with every increase. The temperature is 10 degrees Celsius.

This evaporation increases water vapor in the air, raising humidity levels. On a hot summer day, the sun heats the land and bodies of water, leading to more evaporation and increased water vapor in the air.

Human impact

Besides climatic factors, human factors contribute to higher temperatures and humidity during July and August, and cities with high population densities and infrastructure full of air conditioning units increase local humidity levels due to water vapor emissions.

Cities are warmer than their surrounding rural areas due to the urban heat island effect, where buildings, roads and concrete surfaces absorb the sun's heat during the day and release it at night, making the city warmer than its surrounding areas.

Cities often have fewer trees and green spaces that provide shade and cooling, contributing to increased heat and humidity along with air conditioning, industrial processes and vehicle emissions.

Impact of climate change

With the rise in temperatures caused by climate change, the moisture content in the Earth’s air is constantly increasing, and recent studies indicate that our Arab region may face extremely hot and humid conditions by the end of the century, which may make staying outside for more than 6 hours unbearable in some areas. Countries. According to a study from NASA, extreme levels of heat stress have doubled over the past 40 years, and this trend is expected to continue. Since 2005, wet bulb temperatures have exceeded 35°C for short periods in several regions of the world, including the Arabian Gulf, which is a dangerous indicator.

Wet bulb effect

A study published in the journal Nature Climate Change suggests that parts of the Middle East may increasingly exceed the safe wet-bulb temperature threshold as the end of the century approaches. But what is a wet-bulb temperature? In extremely hot and humid conditions, the body finds it difficult to get rid of heat because sweat does not evaporate effectively, and this point worries scientists.

Wet bulb temperature is a measure that combines temperature and humidity, and the higher it is, the more viscous and hotter the air becomes. Wet bulb temperature is the lowest temperature the human body can reach when moisture evaporates from it. The lower it is, the easier it is for the body to cool, and the higher it is, the more difficult it is for the body to cool. If the wet bulb temperature approaches the body's core temperature (about 37°C), the body loses its ability to cool.

A wet bulb temperature of 35°C is the maximum tolerance for humans when exposed to hot, humid weather for at least 6 hours. High wet bulb temperature poses a significant risk because humans rely on sweating to eliminate about 80% of their body heat. When humidity and temperature are high, it becomes difficult to shed excess heat, which can lead to dangerous and fatal heat exhaustion.

In 2022, a study from Harvard University reported that heat stress rates are rising year over year due to global warming. The study showed that even if the Paris Agreement goal of limiting global warming to 2 degrees Celsius is met, exposure to dangerous heat levels is likely to increase by a factor of 3-10 in many regions around the world.

A study published in October 2023 in the journal BNAS found that billions of people would be affected by unbearable heat if global temperature rose by 2 degrees Celsius above pre-industrial levels, especially in northern India, Pakistan, Bangladesh, East Asia, the Arabian Peninsula, and the African Sahel region. Even at a wet bulb temperature of 30.55°C, the negative impact on human health can still be significant, preventing healthy people from performing simple daily activities.