Climatic zones in the Cauca River Valley

Climate zoning based on meteorological indicators is of utmost importance not only to facilitate its study, but because it has special relevance in the planning of various activities, particularly in agriculture in which climate plays a fundamental role (Piri et al., 2017). In a certain sense, climate zoning based on the analysis of various meteorological elements, translated into indices, allows, according to Eslava (1993), to characterize climate conditions and their temporal and spatial evolution. Criterion supported by Lowry (1973), who states that classification is the best tool to define climate. In this regard, classifications such as that of Caldas-Lang (Eslava et al., 1986), that of De Martonne (Eslava et al., 1986a) and even that proposed by Köppen (Eslava et al., 1986b) are based on the appreciation that climate is the convergence of a set of meteorological elements and phenomena and not the effect of just one of them. And although the aforementioned characterizations only consider precipitation and air temperature, Pabón et al. (2001) argue that these variables – one related to humidity and the other to radiation – synthesize the behavior of the climate of a region.

On the other hand, it is pertinent to mention that although the efforts of Eslava et al. were meritorious. (1986) to classify the country's climate, based on the characteristics of the Cauca River valley and the scale used in said studies, in their perspective the entire valley is covered by a single type of climate. This consideration could have some justification in the fact that this valley is an alluvial plain with few differences in altitude and an average annual precipitation of 1200 mm. But it is a fact that, unlike the rest of the national territory, the distinctive characteristic of the Cauca Valley is its warm semi-humid climate (Narváez and León, 2001). climate of the region that allows identifying spatial patterns or areas with supply contrasting climate. If weather is supply, your demand is determined by the specific characteristics of the influencing crop, in this case sugarcane sugar. It was decided, then, that the classification should be based on variables that had a direct effect on the sugarcane agroecosystem.

For this purpose, it was established that, among the environmental factors that affect the growth and survival of plants, light is the most important (Bickford and Dunn, 1972), which is why in this classification particular attention was paid to radiation. global solar energy, which, although it involves a broader wavelength spectrum than that of visible light, has a close relationship with it.
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The study also took into account that the temperature of the environment in which plants, microorganisms and arthropods, mostly ectotherms, grow, determines their development (Willey, 2016), and that air temperature has a marked influence on some parameters associated with quality. o efficiency of sugar cane to generate a special type of disaccharide. For example, in areas of the region with a prevalence of low values ​​of average air temperature, the accumulation of sucrose in the stems of sugar cane increases, as happens in other latitudes (Clements, 1962; Alexander, 1973). In this regard, it is worth mentioning that in the Cauca River Valley the use of thermal amplitude – better known in the regional context as daily oscillation of air temperature – has become widespread to characterize the effect of decreasing air temperature in the nights with respect to the daily maximum. This index or synthetic climate variable considers the effect proposed by Cardozo and Sentelhas (2013), whereby the colder the nights are, the more favorable the ripening conditions are.

Both precipitation and relative air humidity were added to this classification, since the total volume of water fallen in a given period determines the soil moisture regime, defines the natural productivity of a site and guides management and adaptation activities. crops such as irrigation and drainage. On the other hand, the relative humidity of the air reflects the water content in the atmosphere, which can serve as a guide to establish the sites and times of greatest probability of pathogen invasion (eg, Sumida et al., 2019).