Understanding Spain’s Climate: Geographic & Thermodynamic Factors
Climatic Factors Influencing Spain
Climate: The average state of the atmosphere of a place.
Weather: The state of the atmosphere of a place at any given time.
Climate factors are grouped into two categories:
- Geographic factors
- Thermodynamic factors
Geographic Factors
Latitude
Spain is located in the Northern Hemisphere’s temperate zone, resulting in two distinct seasons: summer and winter, separated by spring and fall transitions.
Location
Spain’s location between the Atlantic and Mediterranean, and between Africa and Europe, makes it a crossroads for air masses.
Influence of the Sea
The sea’s influence is limited by its width, its coasts, and the surrounding mountainous terrain.
Terrain
Terrain influences climate through altitude and orientation.
Mountain ranges parallel to the coast limit the sea’s influence, and the east-west orientation of most of the relief hinders air mass movement.
Altitude
For every 100 meters of ascent, the temperature decreases by 0.6 degrees Celsius, resulting in lower temperatures at higher altitudes.
Orientation
Orientation creates contrasts between sunny and shady areas.
- Solana: South-facing areas receive full sun and are warmer.
- Umbria: North-facing areas are always in the shade, making them colder and wetter.
Thermodynamic Factors
Thermodynamic factors are responsible for atmospheric circulation.
Atmospheric circulation is governed by the jet stream at higher altitudes and by surface action centers, air masses, and fronts at lower altitudes.
The Jet Stream
The jet stream is a strong, tubular current of air that flows in a westerly direction at an altitude of 9-11 km. It influences surface weather, depending on its velocity and seasonal movements.
When the jet stream moves quickly, it has an almost zonal path with gentle undulations, leading to storms. When it moves slowly, it describes deep undulations that cause high pressure (anticyclones).
The jet stream mainly affects Spain in winter, as it moves further south. In summer, it moves north and only affects the Cantabrian fringe.
Surface Circulation
Action centers are areas of high and low atmospheric pressure. Air pressure above the surface is measured with a barometer in millibars. Normal pressure is 1013 millibars and is represented by isobars.
High Pressure (Anticyclone)
A high-pressure area surrounded by lower pressure, with winds circulating clockwise, produces stable and dry weather.
Low Pressure (Storm)
A low-pressure area surrounded by higher pressure, with winds circulating counterclockwise, produces unstable and humid weather.
Main Centers of Action
Main action centers include the Azores anticyclone (responsible for dry and sunny weather), the Atlantic and Scandinavian anticyclones, the Iceland depression, and the Gulf of Genoa depression.
Air Masses
Air masses are large volumes of air with specific properties such as pressure, humidity, and temperature. These properties are acquired at their origin before reaching Spain. Air masses can be polar or arctic (cold) or tropical (hot), and they can originate over the sea or inland.
Fronts
Fronts are surfaces separating two distinct air masses. The most important front for Spain is the polar front, which separates tropical and polar air masses.