Glossary of Geography Terms
A
Anticyclone
A high-pressure center (A) where air masses rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. The air moves downwards and spreads outwards on the surface, creating dry and cloudless conditions. A well-known example is the Azores anticyclone.
Aridity
The inverse relationship between temperature and humidity in a given area. Aridity increases with higher temperatures and lower rainfall.
Avenue Flood
A notable, temporary, and often casual torrent of water in a wadi, or dry riverbed, caused by heavy rain at the headwaters. The effects are almost always destructive due to flooding of nearby populations, orchards, and crops.
C
Cork
An evergreen tree with a short, straight trunk and thick cork bark. Typical of Mediterranean pastures, it is more demanding than oak, tolerating only siliceous, moist, and fresh soils. Its distribution in the Iberian Peninsula is concentrated in the pastures of Extremadura, areas of Cadiz and Malaga, and northeastern Catalonia. Its hard wood is harvested for shipbuilding.
Cauce
The bed of a river and its zone of influence, which it occupies permanently or temporarily during floods.
Cerro Witness
A hill with a horizontal top, resulting from differential erosion on a hard, horizontal layer of old rock. Only the summit remains at the original level.
Circo
A more or less circular depression at the head of a valley where large amounts of ice naturally accumulate, forming a glacier. The base of the circo, the accumulation zone, is enclosed by a steep rocky slope or threshold. Pyrenean mountain lakes are remnants of small glaciers whose circos are filled with water.
Climate
The study of different weather patterns in a place over a period of at least 30 years. Meteorology is the science that studies weather.
Climate Elements
Observable and measurable aspects of the atmosphere that define a particular climate. These include temperature, pressure, precipitation, humidity, cloudiness, solar radiation, evapotranspiration, and aridity.
Climate Factor
Constant and invariable mechanisms that influence the behavior of the atmosphere, such as location and latitude.
Climax Vegetation
Vegetation that emerges spontaneously in relation to the natural environment without human intervention and, therefore, has not suffered any degradation. This is considered ideal vegetation.
Jet Stream
An undulating, eastward-flowing current of air circling the Earth at about 9 km altitude in the troposphere. It has an average speed of 200 km/h and typically occurs in the mid-latitudes, varying in latitude depending on the season and the position of cyclones and storms.
D
Delta
A triangular landform at a river’s mouth, created by the deposition of silt and sediment. The river splits into several branches, which can shift due to continuous deposition.
Depression
A low-pressure center where winds rotate counterclockwise in the Northern Hemisphere. These are areas of converging winds, producing unstable and often rainy weather.
Dune
A hill-like formation built by the accumulation of wind-transported sand. Dunes are characterized by their mobility, sometimes moving up to 30 meters per year. The windward side of a dune is more elongated and less steep than the leeward side.
Drought
A period of time, typically the summer season, during which a river reaches its lowest flow. This is very marked in Mediterranean rivers with a rain-fed regime.
E
Endorheic
Describes areas where water from rainfall, rivers, or seas flows into a specific area without any drainage, resulting in more or less permanent waterlogging. Endorheic areas can include waterways like lakes or streams, as well as mixed areas like wetlands, deltas, and coastal lagoons.
Encina (Holm Oak)
An evergreen tree with thick, cracked gray bark and dark green leaves that produces dark brown acorns. Widespread in the Iberian Peninsula, it adapts to poor soils, withstands cold winters and hot summers, and can tolerate rainfall below 300 mm. Its wood is valued for exterior carpentry, and its fruit, the acorn, is used for livestock feed.
Erosion
The process of wearing away, modifying, and tearing down landforms by erosive agents, which can be climatic (water, ice, and wind) or biological (plants, animals, and humans). The resulting landforms are called erosional landforms.
Evaporation
The physical process by which water becomes vapor at ambient temperature.
Evapotranspiration
The loss of moisture from the Earth’s surface due to evaporation and transpiration from living organisms.
Exorheic
Describes areas where water from rainfall, rivers, or karst systems flows into the sea through a river network.
F
Failure
A rupture in the Earth’s crust, separating blocks of rock. In normal faults, one block rises while the other sinks. The displacement is usually at an angle to the horizontal, called the “dip.” If the displacement is horizontal, the fault is strike-slip. A fault with three blocks, where a central block sinks (graben) and the two sides rise (horst), is called a graben fault.
Flurry
Sediment carried by rain, streams, and rivers, consisting of clay, silt, sand, and gravel. This sediment is deposited when rivers lose their carrying capacity, forming bars along the channel. Over time, this creates fertile alluvial plains useful for agriculture.
Fohn Effect
The effect that causes orographic rainfall. This usually occurs in watersheds open to the sea. Warm, moist air from the sea is forced to rise over a mountain barrier. As it rises, the temperature decreases, causing condensation and precipitation. A dry wind descends on the leeward side, causing abnormally high temperatures.
Fold
A ripple in the Earth’s crust resulting from the continuous deformation of materials by plate tectonics. A fold includes the hinge (line of maximum curvature), axial plane (plane of the hinge), and flanks (surfaces on the sides of the hinge).
G
Garriga
A formation of low shrubs and bushes that leave areas of ground uncovered, exposing the rock. Characteristic plant species include thyme, rosemary, and lavender.
Graben
The sunken central block in a graben fault.
Gully
Narrow and deep clefts with separated edges that create a rugged topography, like a miniature mountain range. These form in clay areas with little plant protection, where long dry periods alternate with heavy rains that erode the slopes. If extended over a wide area, this forms a badlands landscape.
H
Heat Stroke
The amount of solar radiation received by a given area. In Spain, due to its latitude, maximum solar radiation occurs in summer and minimum in winter. The degree of insolation affects temperatures and precipitation in an area.
Hoz (Gorge)
A deep, narrow valley with steep slopes carved by a river in limestone areas. Famous examples in Spain include the Cabriel River gorges in Cuenca and the Duratón in Segovia.
I
Isobar
Lines connecting points of equal atmospheric pressure, fundamental to weather maps.
Isohyet
Lines connecting points of equal precipitation over a land area.
Isotherm
Lines connecting points of equal temperature.
K
Karst
The most common landform in limestone areas, shaped by the dissolving action of water. Water dissolves and seeps through cracks in the limestone, creating caves and canyons. The collapse of these materials forms sinkholes and torcas. Stalactites and stalagmites form in caves due to the precipitation of dissolved calcium carbonate. Surface solution results in sinkholes or lenar (long, sharp furrows) and closed valleys or poljes (horizontal paths with a stream of water that disappears into a drain or ponor).
L
Leeward
The side or space sheltered from the prevailing winds. When air encounters a mountain barrier, the contact slope is the windward side, and the opposite is the leeward side. Leeward slopes usually have lower moisture content than windward slopes.
M
Macchia (Maquis)
Dense, almost impenetrable shrubland, over two meters high, formed by sclerophyllous shrubs such as rockrose, heather, mastic, and broom.
Marisma (Marsh)
A plain whose waters come from a river or the sea, depending on the season. Marshes are formed by river sediments or marine invasions during high tides. In Spain, typical marshes are found at the mouth of the Guadalquivir River.
Meander
A curve in a river’s channel, typically found in the middle or lower course where the current is slower, allowing for changes in the banks. Well-known examples include the meanders of the Tagus River in Toledo and the Guadalquivir River in Córdoba.
O
Oceanity/Continentality
The consequences of a location’s proximity to the ocean, affecting its climate. Coastal areas have milder temperatures and higher humidity due to the influence of large bodies of water.
Orographic Effects
The influence of terrain on climate and vegetation.
P
Páramo (Moorland)
Flat, high structural surfaces topped by a layer of erosion-resistant material. The platform has a horizontal top and gently sloping sides towards the valley bottoms, a result of differential erosion. An example is the moorlands of Burgos.
Peneplain
A gently undulating surface with little height difference between valleys and watersheds, generally formed by the erosion of old basement rock.
Perennial
Describes plants that do not reduce their vital activity in winter and therefore retain their leaves year-round.
Plateau
A plain situated above sea level, generally above 200 meters. The Iberian Plateau is a good example.
Polar Front
The contact surface between a mass of very cold polar air and warmer tropical maritime air. It usually affects the Iberian Peninsula during the spring and autumn equinoxes, producing heavy rain.
Precipitation
Water falling from clouds in liquid or solid form, measured in millimeters or liters per square meter.
Atmospheric Pressure
The weight of the air column over a unit area, measured in millibars (mb) with a barometer. Normal pressure is 1,013 mb.
R
Rambla
A dry riverbed that can unexpectedly fill with water due to intense local rainfall. Typical of arid and desert areas, such as the provinces of Almeria, Murcia, and Alicante.
Ria
A collapsed river valley near the coast, flooded by the sea due to orogenic movements. Saltwater can penetrate up to 30 km inland.
River System
The pattern of water flow in a river, reflecting variations in flow (drought, flood) and seasonal changes. In Spain, there are three main river systems: nival (fed by snowmelt), pluvial (fed by rainfall), and mixed (nival-pluvial or pluvial-nival).
S
Sclerophyllous
Describes plants adapted to aridity and drought, with evergreen, hard, thick, and leathery leaves to minimize evapotranspiration and deep roots to seek moisture.
Sediment/Sedimentation
The deposit of solid materials on the Earth’s surface or in the sea, derived from the disintegration of rocks (detrital sedimentation) or dissolved substances (chemical sedimentation).
Sedimentary Rocks
Rocks formed on the Earth’s surface from materials transported and deposited by erosive agents. They exhibit layers or strata and sometimes contain fossils.
Solana
The south-facing slope of a mountain, ideally oriented east-west. It receives more sunlight, resulting in lower humidity.
Soil
The uppermost layer of Earth, composed of weathered rock material. It is a dynamic layer with distinct horizons: O horizon (plant cover and humus), A horizon (dark layer where plants root and humus is produced), E horizon (light-colored layer where materials are deposited or leached by water).
T
Thermal Amplitude
The difference between the maximum and minimum temperatures of an area over a period of time. The annual temperature range is the difference between the mean temperatures of the warmest and coldest months.
Tributary
A natural watercourse that flows into another river.
U
Umbría
The north-facing slope of a mountain, ideally oriented east-west. It receives less sunlight, resulting in higher humidity.
V
Vertical Temperature Gradient
The normal rate of temperature decrease with increasing altitude, statistically estimated at 0.6°C per 100 meters. This rate can vary depending on geographical factors.
W
Watershed
The territory whose waters flow into a main river and its tributaries. Watersheds are separated by the terrain’s topography, with summits and slopes acting as divides.
Windward
The side or space directly exposed to the prevailing winds. When air encounters a mountain barrier, the contact slope is the windward side, and the opposite is the leeward side. Windward slopes usually have higher moisture content and experience greater erosion than leeward slopes.
X
Xerophytic
Plant species adapted to arid and dry conditions, such as cacti.