Climate of Spain and the Canary Islands
The warm current of the Gulf of Mexico influences the Galician coast, providing warm water. A branch breaks off and heads west towards the Canary Islands. While encountering warmer waters to reach the archipelago, this current, known as the Canary Current, has lower temperatures than the surrounding water body. This temperature difference increases air stability during summer.
Relief
The orientation (upwind or downwind) and height of the terrain influence thermal gradients. The primarily zonal orientation facilitates the entry of maritime air masses from the west. The peninsula’s massive landmass weakens these air masses as they penetrate inland, obstructing the passage of southern continental air masses. The relief also determines orographic precipitation.
Climatic Elements
Sunshine and Clouds
Spain receives abundant solar energy, peaking in summer and reaching its minimum in winter. Sunlight is less intense in the north and increases towards the south. The areas with the most radiation are Extremadura, the Guadalquivir Valley, the Mediterranean coast of Malaga and Murcia, and the Canary Islands.
Temperature
Temperatures are mild near the sea and decrease inland. Key temperature-related climate factors include the annual temperature range, which is the difference between the warmest and coldest month’s temperatures. Frosts occur when air temperatures fall below 0°C due to radiation or advection.
Air Humidity
Humidity refers to the amount of water vapor in the air. It decreases with increasing temperature. Fog forms when atmospheric moisture condenses in the bottom layer. Haze occurs when a significant amount of dust is present in the air, often forming during summer under anticyclonic conditions.
Pressure and Wind
Atmospheric pressure is the weight of air above a unit area and depends on the characteristics of air masses. On the mainland, high pressure dominates in winter, while low pressure prevails in summer. Inland, low thermal pressure systems develop. The Canary Islands experience high pressure, which shifts south in winter and can give way to Atlantic storms. Winds result from pressure differences, flowing from high to low pressure areas. The peninsula lies within the zone of westerly winds. Several local winds exist, and the trade winds, originating from the eastern edge of the Azores High, dominate in the Canary Islands.
Rainfall
Rainfall is water that falls from clouds. It increases with altitude and on windward slopes, being higher in the western half of the peninsula. Spain has three distinct rainfall zones:
- Over 800 mm: Along the northern strip, with most areas exceeding 1,000 mm.
- Between 600 and 800 mm: South of the Pyrenees and Cantabrian Mountains, and just north of Extremadura and the Gulf of Cadiz.
- Under 600 mm: In the Duero basin, the Ebro Valley, Castilla-La Mancha, under the Guadiana River, and most of the Guadalquivir Valley.
Evapotranspiration, Evaporation, and Aridity
Evaporation is the transition from liquid to vapor at ambient temperature. High temperatures favor evaporation, making it more prevalent in summer. Evapotranspiration also occurs through plant transpiration and soil evaporation. Aridity represents the interaction of heat and moisture. Several indices calculate aridity, including the Gaussen index, which measures monthly aridity, and the Meyer-Lantensach index, which determines an area’s dryness based on the number of months with a water deficit. Areas with no monthly water deficit are considered non-arid. Semiarid areas have one to six dry months, while extreme semiarid areas have seven to eleven dry months. Spain has no totally arid regions.
Mountain Climate
Mountainous regions receive over 1,000 mm of annual rainfall, with no dry months (except for one in summer). The annual average temperature is below 10°C, with cold winters and no month exceeding 22°C. Peaks above 1,000 meters experience thermal inversion.
Canary Islands Climate
The Canary Islands have low annual rainfall, between 150-300 mm, peaking in winter. A drying trend is observed in the western islands. Middle and upper zones receive 1,000 mm annually. No month has a temperature below 17°C, and the temperature range does not exceed 8°C.
Local Microclimates
Local microclimates vary depending on latitude, proximity to the sea, and specific local conditions. Terrain variations influence environmental conditions, affecting the climate. Cities experience the impact of asphalt, heating, and car emissions.