The Arab World | What is the Red Sea Depression and how does its impact affect weather patterns during the fall?

Arab Weather - With the onset of autumn, the amount of solar radiation and solar heating on the Arabian Peninsula decreases due to the tilt of the sun's axis, which leads to the beginning of the gradual weakening of the seasonal thermal depression, which controlled the Arabian Peninsula and the Levant in the summer. Giving the opportunity for the Red Sea depression to extend towards the region, which brings many weather phenomena.

What is the Red Sea Depression?

The Red Sea Depression is known as a thermal depression that depends on the thermal differences in its formation, deepening, and decay or shrinkage, which arise between the surface temperature of the waters in the Red Sea basin and the temperature of the land in the Arabian Peninsula and Sudan. The Red Sea Depression is considered a subsidiary extension of the seasonal thermal Sudan Depression.

Surface pressure values decrease in normal conditions with increasing temperatures, which explains why the Red Sea depression shrinks, weakens, and retreats to the south (towards the southern Red Sea and eastern Sudan) in the summer, and deepens and expands to the north in the fall, winter, and spring.

What are the conditions for the deepening and shrinkage of the Red Sea depression?

Red Sea Depression Conditions

When the heat intensifies in the summer months on the Arabian Peninsula, the temperature of the land becomes higher than the temperature of the water surface in the Red Sea, which leads to the filling of the atmospheric pressure and its values in the sea, at the expense of the deepening of the seasonal Indian low in the east and southeast of the Arabian Peninsula. This is called the contraction of the Red Sea low in the summer and its retreat to the south.

Red Sea Depression Extension Conditions

In the fall, specifically in the second half of September, the weather becomes more moderate in the Arabian Peninsula, and the surface pressure begins to fill (pressure values increase and the seasonal Indian low subsides) as a result of the decrease in the temperature of the Earth’s surface in the Arabian Peninsula, which creates a suitable environment in the Red Sea for the decrease in surface pressure, and this is what is called the deepening of the Red Sea low and its extension to the north.

The favorable weather conditions of the Red Sea depression continue during the period between mid-September and early May of each year.

How do the effects of the Red Sea depression affect the atmosphere?

Arab Weather explains that the Red Sea depression is a thermal depression, and its characteristics do not follow frontal or tropical depressions, and its expansion north and east depends on the movement of cold upper basins that rush from the north, and the effect of the Red Sea depression is in the form of:

High temperatures and dry weather

The Red Sea depression causes high temperatures, and heat waves may occur when its extension is strong. It also causes dry and dusty weather, and dust waves may form at times, as a result of the easterly to southeasterly winds blowing.

Causes atmospheric instability when suitable weather conditions are available

If the cold upper basins rush from the north towards the eastern basin of the Mediterranean Sea and northern Egypt and move eastward, the Red Sea depression responds, as moisture rushes from tropical regions of the African continent and the Arabian Sea.

The warm air currents resulting from the expansion of the Red Sea depression in the lower layers of the atmosphere meet with the cold air currents in the upper layers of the atmosphere, coinciding with the rise in humidity levels in the atmosphere.

When this meeting occurs, unstable weather conditions arise, resulting in thunderstorms. It is worth noting that this is the main reason behind the increased chances of floods forming in the fall.