61
climatic variation
cles. The 1 : 1 layer type (one tetrahedral sheet and one octahedral sheet) or
2: 1 layer type (two tetrahedral sheets and one octahedral sheet) clay minerals have silicon in tetrahedral and aluminum in octahedral coordination.
Silicon and aluminum can be replaced by other ions of a different valence
providing a charge to the clay mineral layers. The excess charge within the
layer may cause adsorption of exchangeable cations (Ca, Na, Mg, K, etc.).
Clay minerals are formed chiefly by weathering and hydrothermal action.
The most common mineral groups are kaolinite, illite, smectite, and chlorite.
clearance rate ~filter feeders.
climate the totality of the weather conditions at a certain location over a certain
period (conventional: 30 years). The study of the climate involves the
description and classification of the weather as well as the investigation of
the physical basis for the climate and its differences and variations. One may
describe the climate according to certain larger climatic zones, whereas the
effect of local conditions is reflected in the meso- or microclimate. The
marine climate is strongly influenced by the air-sea exchange and is more
homogeneous than the climate on land. In the tropics (about 10 ON -10 OS)
light winds and high temperature and humidity prevail (doldrums). To the N
and S the following zones are found: the trade winds, up to 30° with persistent NE- or SE-ly winds and with a chance of tropical cyclones, the arid "horse
latitudes" with light winds up to 35°, the westerlies up to 60° with from west
to east traveling disturbances and large weather variations, and the easterlies
from 60° polewards, where the predominant wind direction changes to east.
Geographic conditions modify this pattern, especially in the monsoon region.
climatic variation the climate is not stable. Studies of historical weather records
and geological evidence, such as, e.g., isotope stratigraphy, show that there
have been significant changes in the course of time, sometimes leading to a
glacial epoch. External causes, like orbital variations cannot always be indicated.
For instance, the EI Nino effect in the tropical Pacific appears to be a natural
oscillation involving the interaction between the atmosphere and the ocean.
During the last decades there has been increasing concern about the effects
of deforestation, overgrazing, desertification, rise of carbon dioxide concentration of the atmosphere, etc. on the climate on a global scale. Carbon dioxide
in the atmosphere, together with water vapor and other gases, absorbs part
of the outgoing long-wave infrared radiation. An increase such as has been
observed over a long period of years will lead to an absorption of emitted
and backscattered infrared radiation (~greenhouse effect) and may result in
higher temperatures. In evaluating this effect quantitatively, the oceans play
an important role as a sink of carbon dioxide, while equally the resulting
changes in the circulation in the ocean may be of influence.
climatic variation
cles. The 1 : 1 layer type (one tetrahedral sheet and one octahedral sheet) or
2: 1 layer type (two tetrahedral sheets and one octahedral sheet) clay minerals have silicon in tetrahedral and aluminum in octahedral coordination.
Silicon and aluminum can be replaced by other ions of a different valence
providing a charge to the clay mineral layers. The excess charge within the
layer may cause adsorption of exchangeable cations (Ca, Na, Mg, K, etc.).
Clay minerals are formed chiefly by weathering and hydrothermal action.
The most common mineral groups are kaolinite, illite, smectite, and chlorite.
clearance rate ~filter feeders.
climate the totality of the weather conditions at a certain location over a certain
period (conventional: 30 years). The study of the climate involves the
description and classification of the weather as well as the investigation of
the physical basis for the climate and its differences and variations. One may
describe the climate according to certain larger climatic zones, whereas the
effect of local conditions is reflected in the meso- or microclimate. The
marine climate is strongly influenced by the air-sea exchange and is more
homogeneous than the climate on land. In the tropics (about 10 ON -10 OS)
light winds and high temperature and humidity prevail (doldrums). To the N
and S the following zones are found: the trade winds, up to 30° with persistent NE- or SE-ly winds and with a chance of tropical cyclones, the arid "horse
latitudes" with light winds up to 35°, the westerlies up to 60° with from west
to east traveling disturbances and large weather variations, and the easterlies
from 60° polewards, where the predominant wind direction changes to east.
Geographic conditions modify this pattern, especially in the monsoon region.
climatic variation the climate is not stable. Studies of historical weather records
and geological evidence, such as, e.g., isotope stratigraphy, show that there
have been significant changes in the course of time, sometimes leading to a
glacial epoch. External causes, like orbital variations cannot always be indicated.
For instance, the EI Nino effect in the tropical Pacific appears to be a natural
oscillation involving the interaction between the atmosphere and the ocean.
During the last decades there has been increasing concern about the effects
of deforestation, overgrazing, desertification, rise of carbon dioxide concentration of the atmosphere, etc. on the climate on a global scale. Carbon dioxide
in the atmosphere, together with water vapor and other gases, absorbs part
of the outgoing long-wave infrared radiation. An increase such as has been
observed over a long period of years will lead to an absorption of emitted
and backscattered infrared radiation (~greenhouse effect) and may result in
higher temperatures. In evaluating this effect quantitatively, the oceans play
an important role as a sink of carbon dioxide, while equally the resulting
changes in the circulation in the ocean may be of influence.