Flash floods : Spain
Millions have been affected in Spain due to torrential rain. Flash floods caused by the immense deluge have led to the death of at least 64 people in the eastern Spanish region of Valencia.
- The primary cause of the intense rain is likely an annual weather phenomenon known as a “gota fría,” or cold drop.
- It is also sometimes called a “DANA,” the acronym for “depresión aislada en niveles altos,” or isolated depression at high altitudes.
- DANA or cold drop takes place when cold air descends over the warm waters of the Mediterranean Sea.
- This results in atmospheric instability, causing hotter, moist air on the surface of the sea to rise quickly, leading to the formation of dense, towering cumulonimbus clouds in a matter of hours. These clouds then dump heavy rain in parts of Spain.
- The weather pattern’s occurrence is related to the polar jet stream — a fast-moving wind current at high levels of the troposphere (the lowest layer of Earth’s atmosphere) which circulates from west to east and separates the cold polar air from the warm tropical air.
- Often, a pocket of cold air gets separated from the polar jet stream and collides with the warmer air over the Mediterranean Sea, which results in DANA.
- The phenomenon is a common occurrence in Spain and usually coincides with the onset of autumn and spring in the western Mediterranean.
