Climate and Landscapes: Earth’s Atmospheric Dynamics

Posted on Dec 17, 2024 in Geology

Climate Notes: Catalonia and Earth’s Atmospheric Dynamics

Catalonia, located in the southwest of the Eurasian plate, falls within the temperate zone of the Earth’s atmospheric dynamics. According to the theory of continental drift, or plate tectonics, there are seven major plates:

  • North American Plate
  • South American Plate
  • African Plate
  • Eurasian Plate
  • Indo-Australian Plate
  • Antarctic Plate
  • Pacific Plate

In addition, there are mid-ocean ridges, which are the boundaries between different plates:

  • Mid-Atlantic Ridge
  • East Pacific Rise

The movement of these plates explains the formation of reliefs, earthquakes, volcanoes, and other geological phenomena.

Earth’s Climate and the Formation of Natural Landscapes

The Earth’s rotation determines day and night, while its revolution around the Sun determines the seasons. In addition to these movements, the Earth’s climate is determined by various elements and factors.

Elements

  • Temperature: Measured in °C, it indicates the heat at a given point on Earth.
  • Precipitation: Measured in ml/m², it indicates the rainfall in a particular place.
  • Atmospheric Pressure: Measured in millibars (mb), with values above 1016 mb indicating high pressure and values below 1016 mb indicating low pressure or storms.
  • Wind: Measured in km/h, it determines the air speed at a given site.

Factors

  • Latitude: The distance from the equator (0°), ranging from 0° to 90° North and 0° to 90° South. The Tropic of Cancer is at 23° North, the Tropic of Capricorn at 23° South, the Arctic Circle at 66° North, and the Antarctic Circle at 65° South.
  • Altitude: The distance above sea level, which is considered level 0.
  • Orientation: The position relative to the cardinal points. For example, a mountain facing north is said to be in the shade (umbra), while one facing south is said to be in the sun (solana).
  • Distance to the Sea: The distance to the ocean determines continentality, influencing the climate’s characteristics.

Both elements and factors determine the planet’s climatic zones and vegetation areas.

Water Resources

Water resources consist of surface water, such as lakes and rivers, or groundwater, which flows beneath the surface and is accessed through wells or springs. In the Lleida region, groundwater is often used for irrigation, especially for crops that are not drought-resistant. Misuse of these water resources can lead to soil salinization.

Within surface waters, the hydrographic network in Catalonia can be divided into three main parts:

  • Pyrenean Network: These are the longest and most abundant rivers, originating in the Pyrenees and flowing into the Segre River, which in turn flows into the Ebro River. Examples include the Noguera Pallaresa and Noguera Ribagorzana. These rivers have a nival regime, meaning they are fed by snowmelt.
  • Pyrenean-Mediterranean Network: These rivers originate in the Pyrenees and have a medium to long course, flowing into the Mediterranean Sea. Examples include the Muga, Fluvià, Llobregat, and Ter. These rivers have a nivo-pluvial regime, meaning they are fed by both snowmelt and rainfall.
  • Mediterranean Network: These rivers originate in the pre-coastal or coastal mountain ranges. They are very short and have a low flow. Examples include the Francolí, Gaià, Foix, Besòs, and Tordera. These rivers are born very near the sea and have an irregular regime, meaning their flow is not constant. They are often characterized by torrential flows and are influenced by storms.
  • Ebro River Network: The Ebro River originates in the Cantabrian Mountains and flows into the Mediterranean Sea, passing through rugged terrain. Its course has been modified by the construction of dams.

Classification of Climates

It is important to distinguish between weather and climate. Weather refers to the meteorological phenomena that occur over a short period (a day, a week, a month). Climate refers to the set of meteorological phenomena that characterize a particular place over a long period (typically 30 years).

Climatic Zones

  • Warm: Located between 0° and 23° latitude, further divided into:
    • Humid: Equatorial rainforest
    • Dry: Hot deserts, tropical dry
  • Temperate: Located between the tropics and the Arctic Circle (23° to 65°), further divided into:
    • Humid: Oceanic
    • Subhumid: Continental
    • Dry: Subtropical, Mediterranean, temperate desert
  • Cold: Located between 65° and 90° North and South, further divided into:
    • Subhumid: Mountain
    • Dry: Polar

Temperatures generally decrease with increasing latitude.

Temperatures also decrease with increasing altitude (thermal gradient).

For every 100 meters of altitude gain, the temperature drops by approximately 0.5°C.