Factors Determining Weather in Spain
Spain is a country with a wide variety of climates, influenced by numerous factors that affect weather elements.
Key Elements of Climate
The key elements that shape Spain’s climate are:
- Insolation and Cloudiness: Due to its latitude, the Iberian Peninsula receives high annual insolation, with the south receiving more than the north, and summer exceeding winter. Cloudiness is generally inversely proportional to insolation, except in mountainous regions where dynamic wind phenomena tend to increase cloud formation.
- Temperature: Average annual temperatures in Spain vary significantly depending on latitude and continentality. Temperatures are typically cooler in the north compared to the south, and cooler on the plateau than on the coasts. Additionally, temperature fluctuations are greater inland than in coastal areas. Differences also exist between the Mediterranean and Atlantic coasts, with the Mediterranean experiencing a larger annual temperature range (water temperatures are much colder in winter than in summer).
- Winds: Prevailing winds in Spain are westerly, carrying warm and humid air. However, specific winds, such as northerly winds (e.g., Tramontana), frequently impact the eastern peninsula. These winds are channeled through the Pyrenees mountain passes, leading to high-intensity winds in certain locations.
- Precipitation: The average annual rainfall in Spain is 600 liters per square meter, but its distribution is highly uneven. In the north (Galicia, Northern Spain, Basque Country, Pyrenees), traditionally known as “wet Spain,” annual rainfall ranges from 800 to 1000 l/m2. In the rest of the country (“dry Spain”), rainfall is below 600 l/m2. Some areas (“arid Spain”) receive less than 200 l/m2 (Almería, Murcia, La Mancha, and areas south of Zaragoza). The “Cold Drop” phenomenon, caused by the constriction of a bend in the jet stream, deserves special mention. This phenomenon traps a pocket of cold, moist air amidst warmer zones, resulting in torrential rainfall over short periods, particularly affecting the Mediterranean region.
Factors Influencing Climate
Permanent features, known as factors, exert a constant and unchanging influence on climate elements (temperature, precipitation, sunshine, cloudiness, humidity, atmospheric pressure, wind, evaporation, and aridity), or they follow limited cyclical variations. These factors are classified as:
- Astronomical Factors: These are constant factors like latitude, or they depend on the Earth’s rotation and translation, such as the amount of solar radiation received. Due to its location in the middle latitudes, Spain experiences temperate climates with two distinct seasons (summer and winter) and two transitional seasons (spring and autumn), generally with high insolation throughout the year.
- Geographical Factors: These factors modify the influence of astronomical factors and contribute to greater climate diversity. The primary geographical factors are maritime and continental influences, along with altitude.
- Maritime Influence: The Iberian Peninsula is situated between two seas with significantly different thermal characteristics (approximately a 5°C difference). Both seas help moderate the temperatures of coastal areas. The sea acts as a temperature regulator (water takes five times longer to heat or cool than land). Additionally, the temperature difference between land and sea generates coastal breezes that help moderate temperature extremes in these areas.
- Continental Influence: This maritime influence does not penetrate far inland due to the orientation of the peripheral relief (Galician Massif, Montes de León, Cantabrian Mountains, Basque Mountains, Pyrenees, Catalan Coastal Range, Baetic System), which acts as a barrier, emphasizing the continentality of the interior.
- Altitude: Altitude significantly influences the climate. Areas at higher elevations experience lower average temperatures than those at lower elevations (temperature decreases by approximately 0.6°C per 100 meters). As mentioned earlier, relief hinders the entry of air masses depending on altitude and the orientation of the mountains. It also modifies the temperature and humidity of air masses. When air masses encounter a mountain range and are forced to rise, they cool, become saturated, and precipitate on the windward side. As they descend the leeward side, the opposite occurs – they warm and dry (föhn effect).
- Thermodynamic Factors: These factors are related to the dynamics of the atmosphere. The most important is the general atmospheric circulation, which has two components: upper-level and surface circulation. Upper-level circulation varies depending on the Jet Stream, while surface circulation is influenced by the Polar Front and Atlantic action centers (e.g., the Azores High, which brings dry and sunny weather). Other anticyclones affecting the peninsula, though less persistent than the Azores High, include the Saharan anticyclone (generating dust clouds), the Central European anticyclone (causing very low temperatures), and the Iberian anticyclone (forming over the Iberian Plateau and causing dry and cold weather). Cyclonic air masses influencing the peninsula include the Icelandic Low, bringing abundant rainfall, particularly to the Cantabrian coast; the Gulf of Genoa Low, which, coinciding with the “cold drop” phenomenon, produces heavy rainfall along the Mediterranean coast; and the Gulf of Cadiz Low, also causing abundant rainfall in that area. Finally, the peninsula is also influenced by disturbances associated with the Jet Stream.