Climate

Climate, from the Greek word klima (κλίμα), is the over all weather pattern for an extended period for any defined geographical location which may be over any size of area up to and including the entire Earth. Climate differs from weather in that on a particular day in a desert, for example, there may be rainy weather, but for most days for many years there is little or no rain—rainy weather for a day in a desert climate for many years. Two places, in other words, like Bombay, India and Vladivostock may both have similar weather for a brief time, such as a cloudless, sunny day, but their climate is extremely different. Put another way, weather may change from day to day or hour to hour, whilst climate is the average weather pattern for many years. Commonly the weather patterns that define a climate are averaged for a period of 30 years.

Climate is also different from season. A season is usually a period of time of months, in which the weather can change drastically. Typhoon season in Asia is very windy and rainy. In some places it may rain a great deal for many months. The reminder of the year, the weather can be virtually without rain.

Climate variables include, precipitation (frost, fog, rain hail storms, snow), humidity (water vapour in the air), wind, amount of sunlight, temperature and other measures of weather.

Climatology

Climatology, the study of climates—long-term patterns of weather, is a combination of atmospheric science, hydrology, geology, meterology, astrophysics (which involves, in relation to climatology, the study of sunspots) and other fields. Global warming, a major focus of climatology, is studied to determine its causes and potential effects. Current theories concern natural causes, such as the effects of the sun (i.e. heliogenic global warming), or man-made (i.e. anthropogenic global warming).

Paleoclimatology

Paleoclimatology is the study of ancient climates. Different types of rock and minerals form under specific climatic conditions: wet and dry, warm and cool. This is also true of ancient life forms whose presence may be determined from the fossil record. As the earth’s surface changes climatically and continents move tectonically, the amount of sunlight will vary and effect conditions on the surface, leading to changes which then become buried in the strata. Coal deposits develop under wet conditions, bauxite deposits are evident where it was warm and wet, evaporites and calcretes occur under warm and dry conditions, and tillites where it was wet and cool. The ancient distribution of different rock types provide evidence of how the global climate has changed through time and how the continents have travelled across climatic belts.

Microclimate

Microclimates are distinctive, small-scale climates that are specific defined areas, such as valley’s or regions on either side of a geological feature such as a mountain range that alters the precipitation, wind, sunlight, humidity to such an extent as to make the locale climatically different from the surrounding areas. A heavily wooded park within in an industrialized urban setting will differ climatically from the surrounding buildings and paved areas, a valley branching off a large region of desertification may offer significant climatic variables.

Over time, plants and animals may adapt to these different microclimates to such an extent that they may thrive in a small defined area with a specific microclimate and yet if they are moved a short distance they will languish and show reduced growth and health, possibly even reduced abilty to multiply.

Microclimate may also refer to artificially controlled environments such as homes, office buildings, botanical gardens, archives or museums where specific requirements are not naturally available.

Artificial microclimate

Urban Regions

Urban heat islands are microclimates created by urban areas that are composed of large amounts of building materials, machinery and artificial desertification. Buildings and paved areas such as streets and parking lots do not absorb rainwater and retain heat generated by solar radiation. Industry and vehicles also generate significant amounts of heat. The decrease in vegetation and increased non-absorbent building materials also increases temperature as a result of reduced humidity caused by decreased evaporation from natural sources. The process of evaporation uses latent heat and reduces temperature. Urban areas also generate pollution, introducing large concentrations of naturally and non-naturally occurring atmospheric gases.