Key Meteorological and Geographical Terms Defined
Key Meteorological and Geographical Terms
Weather and Climate
Weather: The daily manifestation of the state of the atmosphere, which humans perceive. It’s the atmospheric state we experience daily, and it differs from one day to another. Meteorology is the science that studies the weather.
Climate: The permanent atmosphere of a territory, represented by average values of weather elements, calculated with datasets of at least thirty years.
Anticyclone: A zone where atmospheric pressure is high, higher than the surrounding air. The air descends from the upper layers of the atmosphere to the Earth’s surface, creating stability and a lack of rain.
Depression (Borrasca): An area where atmospheric pressure is lower than the surrounding air. Due to this low pressure, air rises toward the upper layers of the atmosphere, resulting in instability and precipitation.
Windward and Leeward: On a mountain or mountain range, the windward slope is oriented in the direction of prevailing winds, experiencing greater humidity. In Spain, the windward side of the Atlantic area faces west, and the Mediterranean area faces east. The opposite, drier slope is called leeward.
Foehn Effect: A phenomenon that occurs when a mass of warm, moist air is forced to rise due to a topographic elevation. As it ascends, the water vapor cools, causing condensation and precipitation on the windward slope. The dry air then descends the leeward side, warming as it decreases in altitude.
Humidity: The amount of water vapor present in the air. It can be expressed as absolute or relative humidity. Relative humidity defines the maximum amount of water vapor the air can hold at a given temperature. It’s measured as a percentage, with 100% being the maximum.
Warm Gulf Stream: A warm ocean current originating in the Gulf of Mexico. After crossing the Atlantic from southwest to northeast, it tempers the western European coasts, from the Atlantic coast of the Iberian Peninsula to Scandinavia.
Geographical Concepts
Isohyet: A line connecting points that have the same average annual rainfall, measured in mm or liters per m².
Isotherm (Annual Average): A line connecting points that have the same average temperature.
Annual Thermal Amplitude: The difference between the average temperature of the coldest winter month and the warmest summer month. Coastal regions have low thermal amplitude throughout the year, as seawater softens temperatures, while the interior has a much greater thermal amplitude.
River Regime: The seasonal variation of a river’s flow. Factors determining the river regime include climate, terrain, soil type, vegetation, and human action.
Drought: The period during which a river’s flow reaches its lowest point. In Spain, this tends to happen in the summer months. Drought is much more marked in rivers of the Mediterranean watershed due to summer drought.
Endemism: A plant or animal whose range is restricted to a particular territory, which may be a locality, region, country, continent, etc. It can be applied to species, genera, or families.
Weathering: The process that causes the breakage or decomposition of rock due to the action of atmospheric agents or living beings. It can be:
- Mechanical: When the rock fragments without changing its composition.
- Chemical: When chemical reactions change the rock’s initial composition.
- Organic: When plants or animals break the rock.
Habitat: The area where an organism lives, possessing favorable environmental conditions for its development.
Vascular Flora: A term used to denote the set of species of ferns and flowering plants in a region.
Leaching: The process of migration of a soil component by the action of a chemical agent. For example, the washing of soluble salts in the horizon by the action of water.
Illuviation: The process of deposition of organic substances or minerals in the B horizon (accumulation horizon) of soil, originating from the upper A horizon.
Pedogenesis: The process of soil formation, the speed of which depends on factors such as climate, lithology, geomorphology, vegetation, and time.