<p style=";text-align:left;direction:ltr"><strong>Arab Weather -</strong> The autumnal equinox of 2024 falls on Sunday, September 22, at 06:44 GMT. On this day, the length of day and night is equal throughout the globe, marking the beginning of astronomical autumn in the northern hemisphere and the beginning of spring in the southern hemisphere. What are the climatic repercussions on the region?</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>Polar Vortex Rebuilds in Fall</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> As fall begins, less sunlight reaches the North Pole because the Earth's axis is tilted away from the sun. This decrease in solar heating causes temperatures in the polar region to drop, which promotes the formation of cold air. As the temperature differences between the North Pole and surrounding areas increase, low pressure systems develop in the polar region. This decrease in atmospheric pressure contributes to the gradual formation of the polar vortex.</p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>The impact of polar vortex formation on autumn weather in the Northern Hemisphere</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> As the polar vortex builds, cold air stays trapped in the Arctic. But sometimes, the vortex can weaken, allowing cold polar air to flow into temperate regions. This can lead to sudden cold spells during the fall, especially in North America, Europe, and the North Atlantic, leading to increased Atlantic storm activity.</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> <a href="https://www.arabiaweather.com/ar/content/%D8%AA%D9%82%D8%B1%D9%8A%D8%B1-... Report | Tropical Pacific Ocean Temperatures Move from Balance to Cooling, Harbinger of La Niña Growth Next Fall</strong></a></p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>Hot air masses gradually weaken climatically over the Arab world during the fall, but temperature fluctuations increase.</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> As autumn approaches, the solar heating power decreases, leading to the gradual weakening of the seasonal low pressure system that used to control the Arabian Peninsula and the Levant in the summer. Meanwhile, the Red Sea low pressure system begins to extend towards the region, bringing with it warm air currents. At the same time, cold air masses from Eastern Europe rush towards the Eastern Mediterranean. These cold air masses lose some of their coldness as they pass over the Mediterranean, affecting the region unevenly.</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>Why do the chances of rain and floods increase climatically during the fall in the Northern Hemisphere?</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> The chances of rain increase during the fall season due to the activity of atmospheric instability. These weather conditions are characterized by their random nature, as areas may witness heavy rainfall in narrow geographical areas, while other nearby areas remain completely dry. Heavy rainfall in a short period of time may lead to the formation of flash floods in some areas, especially in low-lying areas.</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>Climatically, the impact of low pressure systems increases with the end of autumn.</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> As the fall season ends, the northern hemisphere, including the Levant, is more likely to be affected by depressions coming from the west. These depressions, which gradually increase in strength in winter, bring with them regular rain to the countries of the region. This gradual change in weather systems is considered an indicator of the beginning of the transition to winter, as weather systems become more stable and temperatures drop significantly.</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><h2 style=";text-align:left;direction:ltr"> <strong>Autumn is characterized by increased chances of catching a cold and seasonal diseases.</strong></h2><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> Autumn is known as a transitional period that witnesses sharp changes in weather, which leads to an increase in the chances of catching a cold and seasonal diseases such as colds and flu. The rapid change in temperatures, as a result of the conflict between cold and warm air masses, weakens the immune system of many, making them more susceptible to these diseases.</p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> <a href="https://www.arabiaweather.com/ar/content/%D8%A8%D8%B3%D8%A8%D8%A8-%D8%A7... to climate change, the period from June to August 2024 will be the hottest in the world in 175 years. Has the era of global boiling begun?</strong></a></p><p style=";text-align:left;direction:ltr"></p><p style=";text-align:left;direction:ltr"> And God knows best.</p>
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