Weather & Vegetation Vocabulary: A Comprehensive Glossary
WEATHER VOCABULARY
Weather
The state of the atmosphere at a particular place and time. Meteorology is the science that studies weather.
Climate
The regular pattern of weather conditions in a specific location over a long period. Determining a country’s climate requires at least 30 years of observation. Climatology is the science that studies climate.
Barometer
Measures the weight of air above a unit area. It’s measured in millibars and represented on weather maps using isobars. Standard atmospheric pressure is considered to be 1013 millibars.
Isobars
Lines on weather maps connecting points with the same atmospheric pressure. When the difference between air masses is significant, isobars are close together, indicating strong winds. When the pressure difference is small, they are further apart.
Anticyclone or High Pressure
Occurs when air pressure exceeds 1013 millibars. Responsible for dry, sunny, and stable weather. A thermal anticyclone forms when an air mass cools and exerts more pressure on the surface. Anticyclonic areas are wind sources. The Azores High is a major anticyclone affecting Spain.
Squalls or Cyclones (Low Pressure)
Occurs when atmospheric pressure is below 1013 millibars. Responsible for unstable and often rainy weather. Warm air tends to rise, reducing pressure on the surface (thermal low pressure).
Jet Stream
A strong wind current flowing west-east at altitudes between 9000 and 11000 meters. It influences surface weather and has variable speed. When fast (over 150 km/h), its path is nearly horizontal. When it slows, it undulates, creating high-pressure peaks and low-pressure valleys. Some undulations can detach from the main jet. When a cold air cell breaks off and interacts with surface storms, it can cause “cold drops,” leading to floods and torrential rains.
Insolation
The amount of solar radiation received by the Earth’s surface. In Spain, there are contrasts between oceanic climate zones, which receive less sunlight, and the southeast peninsula or the Canary Islands, which receive above-average sunshine hours.
Clouds
The state of the atmosphere when the sky is covered with clouds. In Spain, the cloudiest areas are those with an oceanic climate, while the least cloudy are the Guadalquivir Valley, the southern and eastern Mediterranean, and the Canary Islands. Lines connecting points with the same cloud cover are called isonephs.
Humidity
The amount of water vapor in the air, originating from evaporation. It varies depending on proximity to the sea and temperature. Relative humidity is the percentage of water vapor in the air compared to the maximum it can hold at saturation.
Temperature Range (Annual or Diurnal)
The average temperature difference between the warmest and coldest periods. It’s lower in the Canary Islands, oceanic climate zones, and near the sea. It’s higher inland and in continental climates. It can also be calculated daily or monthly.
Temperature
The degree of heat in the air, measured in degrees Celsius with a thermometer and represented on maps by isotherms (lines connecting points with the same average temperature). Average temperatures are milder near the sea due to its thermoregulatory effect and decrease with latitude, altitude, and continentality.
Frost
Occurs when air temperature falls below 0°C. It can be caused by radiation (ground cooling the air in contact with it) or advection (the arrival of a cold air mass). In Spain, the fewest frosts occur in coastal areas, and the most occur in mountainous areas, the Ebro Valley, and the northern central plains.
Calima
Haze that reduces visibility due to a high concentration of fine dust particles in the lower atmosphere. It’s more frequent in summer during intense heat.
Winds
Horizontal air movement relative to the Earth’s surface, caused by pressure differences between high and low-pressure areas. They travel from anticyclones to depressions. Their strength depends on the pressure gradient.
Climograph
A climate chart representing average temperatures and rainfall in a specific location over a year. Temperatures are shown as a red line graph. Rainfall, measured in liters per square meter, is shown as a blue bar graph.
Aridity
The relationship between heat and humidity in a given area. It increases with temperature and decreases with rainfall. Several indices calculate it. The Gaussen index measures monthly aridity, considering a month dry when twice the average temperature equals or exceeds the total rainfall for that month. The Lautensac rate determines an area’s aridity based on the number of months with a water deficit, considering a month dry when it receives less than 30 liters of precipitation.
- No aridity: Areas with no months of water deficit.
- Sub-humid: 1 to 3 arid months.
- Semi-arid: 4 to 6 arid months.
- Semi-extreme arid: 7 to 11 arid months.
Foehn Effect and Orographic Rainfall
When an air mass encounters a mountain barrier, it’s forced to rise. The ascent causes a temperature drop, and water vapor cools and condenses into clouds, leading to rain on the windward slope (exposed to the wind). After crossing the summit, the air descends but has lost most of its water vapor, resulting in less rainfall on the leeward side.
Fronts
Boundaries separating two air masses with different characteristics. There’s an abrupt change in weather properties across a front. The most important front for Spain is the polar front, separating tropical and polar air masses. Its undulations create storms and precipitation. Fronts can be cold, warm, or occluded.
VOCABULARY OF VEGETATION
Deciduous Forest
A plant formation of trees that lose their leaves in autumn and regrow them in spring. It’s typical of regions with oceanic climates, mild temperatures, and abundant moisture. Characteristic species include beech and oak. This forest type is declining due to human activity and competition from faster-growing species like pine and eucalyptus.
Sclerophyllous Forest
A forest type found in Mediterranean regions, with tree species adapted to the summer drought characteristic of this climate. The vegetation consists mainly of oaks, which have adapted by reducing leaf size, developing hard and leathery leaves to minimize water loss through evaporation, and having extensive root systems to access soil moisture.
Marcescent Forest
A vegetation type where trees retain their dead leaves until new buds emerge. It’s a transitional formation between deciduous and sclerophyllous forests. The main species are Pyrenean oak and downy oak. The shrub layer in this forest is very dense.
Landes
Shrubland resulting from the degradation of deciduous forests. It’s typical of Atlantic climates and consists of species like gorse, heather, broom, and thorny plants.
Maquis
Mediterranean scrubland formed by a dense mass of shrubs, appearing in areas where sclerophyllous forests have been degraded. Characteristic species include mastic, rockrose, heather, and gorse. It predominates in areas with siliceous soils.
Garrigue
Scrubland formation in Mediterranean climates. The species are smaller and less dense than those in maquis. It’s found on flat terrain, often with bare patches of soil. Typical species include thyme, rosemary, and lavender. It’s a more degraded form of vegetation than maquis and mainly occurs on calcareous soils.
Steppe
Shrubland with low, thorny, and drought-resistant species. It represents the most extreme form of plant degradation, typical of arid climates in the southeastern mainland or areas severely degraded by human activity. Characteristic species include thyme, esparto grass, and dwarf palm.
Cliserie
The altitudinal zonation of plant species in mountainous areas. Vegetation changes with altitude due to variations in temperature, humidity, and soil development. Each level of the cliserie has a different type of vegetation adapted to its specific conditions. The zonation also depends on slope orientation (sunny or shaded) and exposure to wind (windward or leeward).
Coniferous Forest
Forest composed of evergreen conifers with needle-like leaves and fruits clustered in cones. Many species of pine and fir are prominent. It naturally occurs in mountainous areas between deciduous forests and alpine meadows. Due to its rapid growth and industrial uses, it’s being planted extensively and is a preferred species for reforestation.
Native Species
Species originating in a particular location. They can be wild when they develop naturally without human intervention. Endemic species are found only in a very specific area. Spain has a high number of endemic species, and their conservation is crucial, as their disappearance could lead to the extinction of the species. Most endemic species are found in mountainous areas above 1500 meters and in the Canary Islands.
Alien Species
Species not native to a territory but introduced through human activity, often for specific purposes.
Rupicolous Vegetation
Vegetation that grows on rocks. Some, like mosses and lichens, live directly on the rock surface, while others grow in cracks and crevices.
Spanish Fir
A highly protected endemic species found in Cadiz, Malaga, and Estepona. It’s a type of fir that requires over 1000 liters of rainfall per year but can withstand dry summers.
Cardonal
A very open plant formation characteristic of arid areas, generally composed of cacti (Canary Islands vegetation).
Tabaibal
A formation consisting of different plant species with succulent stems and a small rosette of leaves at the stem’s end, present only for a short period (Canary Islands vegetation).
Macaronesian
An Atlantic region comprising archipelagos like the Canary Islands, Madeira, and Cape Verde. Due to their island status, proximity to Africa, and unique geology and flora, they constitute a distinct biogeographical region.