DEFINITION OF CLIMATE

The average weather of a place or area, and its

variability over a period of years. The term climate is derived

from the Greek word klima, meaning inclination and referring

specifically to the angle of inclination of the Sun’s rays, a

function of latitude. The average temperature, precipitation,

cloudiness, and windiness of an area determine a region’s climate.

Factors that influence climate include latitude; proximity

to oceans or other large bodies of water that could

moderate the climate; topography, which influences prevailing

winds and may block precipitation; and altitude. All of

these factors are linked together in the climate system of any

region on the Earth. The global climate is influenced by many

other factors. The rotation of the Earth and latitudinal position

determine where a place is located with respect to global

atmospheric and oceanic circulation currents. Chemical interactions

between seawater and magma significantly change

the amount of carbon dioxide in the oceans and atmosphere

and may change global temperatures. Pollution from humans

also changes the amount of greenhouse gases in the atmosphere,

which may be contributing to global warming. Climatology

is the field of science that is concerned with

climate, including both present-day and ancient climates.

Climatologists study a variety of problems, ranging from the

classification and effects of present-day climates through to

the study of ancient rocks to determine ancient climates and

their relationship to plate tectonics. An especially important

field being actively studied by climatologists is global climate

change, with many studies focused on the effects that human

activities have had and will have on global climate. For

many of these models it is necessary to use powerful supercomputers

and to construct computer models known as

global circulation models. These models input various

parameters at thousands or millions of grid points on a

model Earth and see how changing one or more variables

(e.g., CO2 emissions) will affect the others.

Classifications of climate must account for the average,

extremes, and frequencies of the different meteorological elements.

There are many different ways to classify climate, and

most modern classifications are based on the early work of

the German climatologist Wladimir Koppen. His classification

(initially published in 1900) was based on the types of

vegetation in an area, assuming that vegetation tended to

reflect the average and extreme meteorological changes in an

area. He divided the planet into different zones such as

deserts, tropics, rainforest, tundra, etc. In 1928 a Norwegian

meteorologist named Tor Bergeron modified Koppen’s classification

to include the types of air masses that move through

an area, and how they influence the vegetation patterns. The

British meteorologist George Hadley reached another fundamental

understanding of the factors that influence global climate

in the 18th century. Hadley proposed a simple,

convective type of circulation in the atmosphere, in which

heating by the Sun causes the air to rise near the equators and

move poleward, where the air sinks back to the near surface,

then returning to the equatorial regions. We now recognize a

slightly more complex situation, in that there are three main

convecting atmospheric cells in each hemisphere, named

Hadley, Ferrel, and Polar cells. These play very important

roles in the distribution of different climate zones, as moist or

rainy regions are located, in the Tropics and at temperate latitudes,

where the atmospheric cells are upwelling and release

water. Deserts and dry areas are located around zones where

the convecting cells downwell, bringing descending dry air

into these regions.

The rotation of the Earth sets up systems of prevailing

winds that modify the global convective atmospheric (and

oceanic) circulation patterns. The spinning of the Earth sets

up latitude-dependent airflow patterns, including the trade

winds and westerlies. In addition, uneven heating of the

Earth over land and ocean regions causes regional airflow

patterns such as rising air over hot continents that must be

replenished by air flowing in from the sides. The Coriolis

force is a result of the rotation of the Earth, and it causes any

moving air mass in the Northern Hemisphere to be deflected

to the right, and masses in the Southern Hemisphere to be

deflected to the left. These types of patterns tend to persist

for long periods of time and move large masses of air around

the planet, redistributing heat and moisture and regulating

the climate of any region.

Temperature is a major factor in the climate of any area,

and this is largely determined by latitude. Polar regions see

huge changes in temperature between winter and summer

months, largely a function of the wide variations in amount

of incoming solar radiation and length of days. The proximity

to large bodies of water such as oceans influences temperature,

as water heats up and cools down much slower than

land surfaces. Proximity to water therefore moderates temperature

fluctuations. Altitude also influences temperature,

with temperature decreasing with height.

Climate may change in cyclical or long-term trends, as

influenced by changes in solar radiation, orbital variations of

the Earth, amount of greenhouse gases in the atmosphere, or

through other phenomena such as the El Niño or La Niña.

See also ATMOSPHERE; CLIMATE CHANGE; EL NIÑO;

PLATE TECTONICS.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar