Jet Streams, Climate Factors, and Thermopluviometrics in Catalonia
Jet Streams and Atmospheric Circulation
A jet stream is a set of winds within the atmospheric circulation at high altitude, blowing east to west in the same direction as the Earth rotates. These winds can exceed speeds of 500 km/h at heights of 1200 m. The name ‘jet stream’ reflects its shape and intensity. There are two jet streams in each hemisphere.
Factors Influencing Climate in Spain
Several factors influence the climate in Spain:
- Tropical Anticyclones: The action of the general circulation of winds, with their fronts and storms.
- Western Mediterranean: The semiautonomous operation of the Western Mediterranean.
- Shape and Relief of the Peninsula: The physical geography of the Iberian Peninsula.
The Azores anticyclone is a significant tropical anticyclone.
Atlantic depressions (borrascas) are pushed by winds from the west. Their passage over the peninsula causes variable weather, including cloudiness, frequent and abundant rainfall, wind, and mild temperatures.
Polar air masses from the Arctic can cause substantial and rapid decreases in temperature, leading to snow, sleet, and rain in winter. Siberian continental or polar air masses, originating in the center and north of the Euro-Siberian region, produce snow and cold winters.
The behavior of the semiautonomous western Mediterranean also plays a role. Subtropical anticyclones dominate this sea, causing warming of the water and intense evaporation. In the fall, as the anticyclones withdraw to the south, cold air masses enter, creating a thermal difference that generates low pressure in the western Mediterranean. This can lead to condensation and torrential rains.
The shape and relief of the land also affect the climate. The mainland of the peninsula and the arrangement of the relief isolate the interior lands from the sea. The action of subtropical anticyclones intensifies, leading to increased dryness and higher temperatures. In winter, air masses cool significantly when they come into contact with the inland areas.
Importance of the Azores Anticyclone
The Azores anticyclone has a significant impact on the climate of the Iberian Peninsula, serving as the main meteorological center of Spain. The air mass of the anticyclone, when in contact with the sea, becomes a marine tropical air mass. The anticyclone is warm and dry, dominating much of the peninsular region.
Special Thermopluviometric Conditions in Catalonia
Atlantic or oceanic climates are characterized by the influence of the west, resulting in high humidity throughout the year. These are not the only Mediterranean climates.
Dry summers are typical of oceanic climate varieties:
- Mountain Climate: High altitude, low temperatures, abundant rainfall, and frequent winter snow.
- Oceanic Range of Transition: Receives less Atlantic influence, with less rainfall, dry summers, and cold winters.
The Mediterranean climate, within the subtropical domain of anticyclones, causes warm and dry summers. During winter, spring, and fall, the movement of depressions in the middle latitudes brings rain.
Varieties of Mediterranean climates include:
- Atlantic Influence: Abundant rainfall throughout the year, especially during the cold season, and hot, dry summers.
- Typical Mediterranean: Rainfall varies between 600 and 800 mm, with cool winters and mild summers.
- Dry Variety: Less than 400 mm of annual rainfall, dry weather, and a high aridity index with a notable water deficit.