Discuss these terms as used in physical Geography (a) Micro-Climates or Local Climates (b) Man made climates (c) Cloud seeding

a) Micro-Climates or Local Climates
The smallest scale of climate variations can conveniently be termed local climates or microclimates. The spatial range of these varies from a few square centimetres, the conditions around a growing plant to a few square kilometres, the climate of a city. It is the micro-climate which we experience every day that dictates what crops we grow, that determines our home heating and cooling requirements and influences our city drainage system design. It is also on the micro-scale that human beings deliberately modify the
climate to help meet our needs for comfort and also the scale upon which the major inadvertent modifications have already taken place.
The local climate/micro-climate depends for its general characteristics upon the regional climate and ultimately upon the global climate system. It is therefore useful to keep in mind constantly that the local climate of a particular place is a variation of the regional climate. Indeed the mechanisms acting to create a local climate are essentially the same as those creating the global climate. The major differences are those of emphasis. In particular, the character of the surface and how it varies spatially and interacts with the overlying atmosphere are the most vital considerations.
The character of the surface includes aspects such as; the type of surface, whether it be of grass, forest, concrete, or water; the nature and size of upstanding objects such as fences, trees or tall buildings; the general topography of the area and its overall altitude, all influence the surface characteristics and their variations are the major determinant of local differences in the energy balance. The main physical consequence is that there are spatial temperature variations. These are likely to lead to air density and pressure differences, which can create local winds when the regional atmospheric conditions are favourable. These regional conditions are also greatly influenced by the surface characteristics to produce local cloud and precipitation regimes. These not only influence the local water balance but also the local energy balance thus bringing us full circle.

b) Man made climates
The scale of local climate/micro-climate is, by our definition, the scale at which mankind operates. On a local scale humans can modify the climate deliberately or inadvertently, and can take steps to utilise it as a resource or avoid its adverse impacts.
Inadvertent modification of climate involves any change in the surface characteristics by human agency that leads to a climate change. Examples would include the creation of a city or clearing of a forest for farming activity etc. These are essentially local scale phenomena and indeed it is on this scale that the major modifications have taken place.
However, consistent local modifications that take place at a large number of sites could combine to produce coherent regional or even global alternations in climatically important parameters as in global warming.

c) Cloud seeding
This is used for both precipitation augmentation and cloud dissipation. The basis for such modifications is artificial stimulation of the Bergeron-Findeisen process. Cloud seeding can only be undertaken when a cold cloud is already present and so serves as a means of precipitation augmentation, not’ rainmaking’ in an area with no naturally occurring chance of rain. Due to this restriction it is extremely difficult to demonstrate vigorously that a specific cloud seeding project has led to increase in rainfall.
Nevertheless, the balance of evidence suggests that the technique is useful in areas where a small increase in precipitation can lead to significant economic gain. Hence, for example, it is widely practised in the somewhat marginal agricultural areas of the American Midwest and in South Africa. It is also used to augment winter snowfall in the American Rockies, helping to enhance the amount of water in that frozen reservoir, which will become available in subsequent growing season.
Attempts are being made to use cloud seeding techniques to modify the microstructure of clouds as an aid to hail suppression. If a large number of small hailstones can be produced to replace a small number of large ones, there is likely to be a decrease in the damage the hail causes. This technique has been experimented in the tea growing areas of Kericho without much success.

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francis1897 answered the question on October 5, 2022 at 11:10