It is in relation to plant growth and development that the question What is climate? Is here reviewed.
According to Dr. Frits Went (Went and The Editors of Life, 1963), climate is the most important environmental factor affecting plant growth and development. However, any of the various elements that compose climate does not operate singly. Variation in one of these climatic factors can have significant effects on the others and modify the various physiological processes in plants including photosynthesis, respiration and transpiration (click here to read Climatic Factors Affecting Plant Growth and Development).
As to what can be perceived by the eye, the various elements of climate determine whether or not a seed will germinate, grow into a mature plant, or produce flowers, fruits and seeds. It is also the reason for the differential distribution of plant species throughout the world or in any geographical region (click here to read Plant Classifications By Adaptation).
Climate has been defined briefly as the average long-term weather of a place. It is usually determined over a period of 30 years, or more. Weather in turn is the short-time atmospheric condition of a place. It may occur and change within minutes, days or months. Therefore, if the two are combined, climate can be defined simply as the average atmospheric condition of a place as determined over a long period of time.
To be clear, however, climate is not capable of exact determination. Even with the invention of modern meteorological instruments, it is not possible to predict exactly the amount of rain that may fall on a given day or time period. The same is true as to temperature and other atmospheric elements.
According to Eagleman (1985), climate is more than just average weather and that a realistic description ought to include the extremes as well as the average weather. Further, fluctuations can occur which are difficult, if not impossible, to predict.
For example, the eruption of Tambora in Indonesia in 1815 injected tons of volcanic dust into the stratosphere. This resulted to the occurrence of killing frosts every month in 1816, the “year without a summer.” Crop failures resulted to food riots in parts of Europe.
Another volcanic eruption, that of Mount Pinatubo in the Philippines in 1991, resulted to slight cooling of the earth which masked the signs of global warming for about 3 years. The devastating effects of drought and typhoons on farm crops throughout the world are testaments to climate’s unpredictability.
To shed further light on what is climate, here are meanings of the word from a science dictionary:
The Cambridge Dictionary of Science and Technology (1988) gives the following meaning of climate in relation to meteorology: “the statistical ensemble of atmospheric conditions characteristic of a particular locality over a suitably long period (e.g., 30 years) including relevant parameters such as mean and extreme values, measures of variability, and descriptions of systematic seasonal variations. Aspects considered include temperature, humidity, rainfall, solar radiation, cloud, wind and atmospheric pressure.”
In relation to botany, it also provides the meaning of climatic factor as: “a condition such as average rainfall, temperature and so on, which plays a controlling part in determining the features of a plant community and/or the distribution and abundance of animals.”
The above definitions/meanings indicate that climate, indeed, is a composite effect of environmental elements including temperature, humidity, rainfall, etc.; measured or determined over a long period of time; includes averages, extremes, and statistical variability; and affects or influences plant adaptation and diversity.
Poincelot (1980) clarified that climatic data are obtained with the use of instruments that are 2 or more meters above the ground. To distinguish, the term macroclimate is used to refer to the atmospheric climate while microclimate refers to the climate below this level.
The microclimate can easily change and is subject to influences of the surface profile. It is affected by wind, type and compactness of vegetation, soil characteristics, slope, buildings, pavements, and other surface conditions, both natural and artificial.