8 junio, 2024

Thermal floors: characteristics and how they change with altitude

The thermal floors They are the different strips defined by the altitude in a mountain where there are variations in temperature and other elements of the climate. In this case, the determining climatic factor is the altitude above sea level and the main element affected is temperature.

Therefore, the thermal floors define the climatic variations that occur in mountainous areas. In addition, the relief also affects precipitation, since the moisture-laden winds collide with the mountains and rise.

These thermal floors are really appreciated in the intertropical zone, while in the temperate zones they are poorly defined, due to the fact that the temperature in the temperate and cold zones is more affected by the annual variations of solar radiation.

In this context, the altitude variations define significant temperature variations that establish at least 5 thermal floors, the lowest being the warm floor, then the temperate, cold, páramo and icy floors. For each one, an amplitude of variation of height and temperature is determined, as well as other associated characteristics.

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Characteristics of thermal floors

The differentiation in floors or altitudinal levels with defined temperature ranges is clearly expressed in the intertropical zone. While in the temperate zone, although the temperature also decreases with altitude, the effect is not as marked.

This is due to the fact that in temperate zones there are other more determining factors such as latitude, which influences the solar radiation received according to the orientation of the slope. While in the tropics, given the permanent and almost uniform incidence of solar radiation, it affects the effect of winds and rains.

temperature and altitude

The air is heated by heat from the ground (long-wave radiation), which is heated by solar radiation (short-wave). In such a way that the temperature in the troposphere or lower atmosphere, is higher at ground level and decreases as it ascends.

In fact, the average temperature decreases approximately 0.65 to 1 °C for every 100 m that the altitude increases.

Other relief effects

The mountains and their altitude also affect the winds and precipitation, which adds to the characteristics of the thermal floors. This is because if a high mountain stands in the path of the moisture-laden winds, they rise.

In this ascent, if the altitude is high, the winds cool and the humidity condenses, causing precipitation. In the higher mountains, when the winds manage to surpass them, they discharge the humidity in the windward (facing the wind) and the leeward slope (against the direction of the wind) will be drier.

On the other hand, higher humidity promotes more vegetation, which in turn affects temperature.

latitude

The position of an area of ​​land with respect to the equator affects the incidence of solar radiation throughout the year, in such a way that in the intertropical strip it is it is uniform. No matter what position the Earth is around the Sun, the tropical zone always receives its radiation.

While at higher latitudes, either north or south, this does not occur, due to the tilt of the Earth’s axis. That is why in the most extreme latitudes (the poles), the altitude does not substantially alter the temperature because there is low solar radiation.

The thermal floors, temperatures and altitudes

It must be taken into consideration that depending on the authors, between 5 or 6 thermal floors are indicated in the intertropical zone. The fundamental difference is whether or not an additional floor located between 900 and 1,700 meters above sea level, called premontane or semi-warm, is recognized.

Warm or macrothermal thermal floor

It presents high temperatures, in the range of 28 °C average at its lower limit (sea level), and 24 °C at 900 or 1,000 meters above sea level. The ecosystems of tropical rain forest, deciduous and semi-deciduous forests, savannahs as well as arid and semi-arid zones are present in this thermal floor.

This depends both on the latitude within the intertropical strip, and on factors such as winds and proximity to oceans. For example, in the coastal plains moisture is carried inland by sea winds, so they are drier.

While the lowlands located at the equator receive large amounts of rain due to the confluence of humid winds from both hemispheres. On the other hand, in these low regions, when presenting high temperatures, there is greater evapotranspiration and greater humidity available for precipitation.

Premontane or semi-warm thermal floor

In some systems this floor is ignored, including it within the temperate floor, which is located between 900 and 1,700 or 2,000 meters above sea level. It reaches an average temperature between 24 and 18 °C.

At these altitudes, low mountain cloud forests are formed, and orographic rain occurs. That is to say that the ascending air masses condense forming clouds and producing rain.

Temperate or mesothermal thermal floor

The prefix «meso» means medium, referring to what are considered temperatures between hot and cold. This floor is located between 1,000 and 2,000 meters above sea level. if the previous floor is not recognized.

On the contrary, if the existence of a premontane floor is recognized as valid, then the temperate floor would be between 2,000 and 2,500 meters above sea level. Its average temperatures are between 18 and 15 °C, reaching 24 °C as the maximum limit if the premontane floor is also ruled out.

At these altitudes high cloud forests are formed and in subtropical latitudes such as northern Mexico, coniferous forests. The phenomenon of orographic rain and horizontal rains also occurs.

Cold or microthermal thermal floor

This is a floor of low temperatures, on average from 15 or 17 °C to 8 °C, because it is in an altitudinal range between 2,000 or 2,500 to 3,000 or 3,400 meters above sea level. Here the limit of trees is reached, that is, the maximum height at which this form of life develops.

Only the species of the genus Polylepis grow above the limit. At the upper limit, low night temperatures reach the freezing point, which limits the availability of water and increases solar radiation.

Páramo thermal floor

This thermal strip occurs above 3,400 or 3,800 meters above sea level and below 4,000 or 4,500 meters above sea level. Temperatures drop from the average 12 or 8 °C, reaching 5 °C and even 0 °C.

For its part, night temperatures reach freezing and there is even precipitation in the form of snow. Therefore, although in some cases there is sufficient precipitation, the availability of water can be a limiting factor.

This occurs mainly in the highest and driest areas such as the Puna in the Bolivian and Peruvian altiplano, due to the high altitude and being surrounded by mountains. Thus, they are very dry areas, since the winds that arrive there have already discharged all their moisture along the way.

icy floor

It is located above 4,000 or 4,800 meters above sea level and corresponds to the area of ​​perpetual snow. Therefore the precipitations are in the form of snow and the low temperatures prevent its melting despite the high solar radiation.

Thermal floors in Colombia

Being located very close to the equator and having a mountainous relief, in Colombia the thermal floors are manifested in a well-defined way. In this country there is an altitudinal gradient that goes from sea level to 5,775 meters above sea level.

In Colombia, 5 thermal floors are generally recognized, that is, the premontane floor is not considered.

warm floor

This is the floor that covers the largest area in Colombia, since it includes the entire coastal plain of the Caribbean and the Pacific, plains of the Orinoco basin and the plain of the Amazon basin.

It also includes the valleys of the Magdalena, Cauca, Cesar, and Catatumbo rivers, among others, all lands between 0 and 1,000 meters above sea level. The average temperatures are above 24 °C, various types of vegetation are developed and many have agricultural purposes.

These are the lands of the dry forests of the Caribbean coast, the plains of the Orinoco and the hot tropical forests of the Amazon. On the other hand, this thermal floor is suitable for the cultivation of cocoa, sugar cane, coconut, cotton, bananas, cassava, pineapple, mango, among others.

temperate floor

In Colombia it is located in the Andean mountain ranges, including the Sierra de Santa Marta and the Sierra de La Macarena, between 1,000 and 2,000 meters above sea level. There are mean annual temperatures between 17 and 24 °C and the vegetation includes tropical mountain forests and bushes.

While agricultural and livestock activity involves livestock and crops such as coffee, emblematic for this country, as well as corn and different fruit trees.

cold floor

This floor includes the areas of the mountain ranges between 2,000 and 3,000 meters above sea level in the Andean mountain ranges, including the Sierra de Santa Marta. Temperatures range from 17 °C to 12 °C and feature mountain jungles, including high cloud forest.

While in this thermal zone livestock farming is practiced and potatoes, vegetables, corn and other cereals are cultivated, as well as fruit trees such as tree tomatoes, blackberries and curuba.

wasteland floor

Since this floor is located between 3,000 and 4,000 meters above sea level, it is only found in the highest parts of the Andean mountain ranges. There is an average annual temperature between 12 and 5 °C and the vegetation is low, as this strip is located above the tree line.

However, there are groves of the only tree species that exceeds the limit, the yagual (Polylepis spp.). It is mainly shrublands and grasslands, where the genus is characteristic espeletia (frailejones).

This floor is dedicated mainly to the conservation of water sources, although some species such as potatoes, vegetables, varieties of wheat and beans are cultivated.

glacial floor

This is the highest floor, being defined from 4,000 meters above sea level, restricted to the Sierra Nevada de Santa Marta, the Nevado del Cocuy and some peaks of the three main mountain ranges. No type of productive activity is developed, beyond high mountain tourism.

References

Barry, R. and Chorley, R. (1998). Atmosphere, Weather and Climate, London, Routledge.
Camilloni, I. and Vera, C. (s/f). The atmosphere. Natural Sciences. Explore. Sciences in the contemporary world.
Calow, P. (Ed.) (1998). The encyclopedia of ecology and environmental management.
Jaramillo, CA (Gen. Ed.) (2002). World Congress of Páramos. Memories Volume I. Ministry of the Environment.
Kump, L., Kasting, J., & Crane, R. (1999). The Earth System, New Jersey, Prentice-Hall.
Mederos, L. (2018). Meteorology. A book to understand the fundamentals of meteorology. Ed. Tutor.

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