The climatic factors: the temperature


The climatic factors: the temperature

"We Italians, however, are unbeatable when it comes to finding more or less science fiction causes" Guido Visconti from Corriere della Sera on 9/01/00.

Let's try to reason and try to deepen the nature of the factors that determine the various types of climate, in particular on the basis of their "behavior" in past years, and of glimpse possibly how the climate could be in a more or less immediate future, without resorting to science fiction, as Guido Visconti ironically and rightly points out, a judgment that also applies to other nationalities.

The data available for the past and for the geological eras are innumerable, obtainable from paleogeographic and historical sources, as well as from meteorological records when and where made.

In the interpretation of geological, paleontological, paleobotanical, paleoclimatic data, etc. the "Actualism Law" is applied by all, according to which if historical sources report that in a certain area there were certain botanical crops or zoological species today linked to a certain climate, it is concluded that that area was characterized by the same For this reason, if in the Middle Ages the vine was cultivated in England and in the Baltic regions, evidently the climate must have been mild,

and so if at the Port of Leptis Magna in Libya there are the remains of oil pipelines to load on the ships not the crude oil of the oil wells, but the olive oil, it must be concluded that in the interior of Libya in the Roman era there must have been a climate that allowed the cultivation of the olive tree on a large scale that justified the construction of oil pipelines.

If we add to this data that lions (hic sunt leones) circulated freely in the interior of Libya, the current desert climate of the Sahara must have been established by natural causes in more recent times, not suspected of pollution.

Let's start with the climatic factor whose variations are more suitable for invoking ecological calamities and catastrophes, that is: THE TEMPERATURE

Everyone knows what temperature is, how it is measured and what are the most common units of measurement.

It is known that the temperature of the human body varies between 35 and 37 degrees Celsius in normal health conditions, because above 37 ° we begin to speak of fever.

It is known that the water temperature varies between 0 ° C and 100 ° C, as below 0 ° C it becomes ice and above 100 ° C it becomes water vapor.

It is known that for matter the lowest temperature is absolute zero equal to 273.15 ° C, while in the universe the values ​​that the temperature can reach are very high: it is estimated that the sun can touch 15 million degrees centigrade in the center and 6,000 degrees Celsius on the surface. The earth inside with its 4000 ° C retains much of the temperature that in the initial aggregation process the cosmic cloud had reached (see helichrysum January 2000 - Geology and environment), while on the surface the average temperature is around 23 -24 ° C.

Distribution of temperature on the surface of the Earth

Obviously the extreme values ​​will be found between the desert areas and in the glacial areas of the poles. In fact, Azizia (Libya) is mentioned as the highest temperature for decades, where 58 ° C was recorded in 1922. It is a normal temperature for a desert like the Sahara, considering that Azizia is less than 100 km from the coast, and undoubtedly there will have been, in many years, values ​​above 58 ° C not recorded due to the lack of meteorological stations. Obviously lower temperatures were recorded in the polar areas and at high altitudes. The record is reported at Vostok (Russian Station in Antarctica) at 3,488 m a.s.l. where 89 ° C were recorded in 1983.

So the earth's temperature can fluctuate in an interval of at least 150 ° C, but this could be considered more of a curiosity, as what really interests to be able to talk about climate changes are the variations in the average temperature ascertained over a long period. of years and for a sufficiently large area.

With the next issue we will illustrate the data relating to the temperature starting from the last 10 millennia, reconstructing the trend from which it will be possible to see that the much vaunted mild climate of the Mediterranean area and neighboring regions has occurred only occasionally and for limited durations.

Dr. Pio Petrocchi


The climatic factors: the temperature

The climate is the synthesis of the fundamental meteorological characteristics observable in the long term (many decades or hundreds of years). Therefore, the climate of a given territorial area is the representation of the set of statistics, referring to a given time interval, of all those meteorological phenomena, individually taken or correlated with each other, which in their typical or characteristic trends constitute the "norm ". The causal factors underlying the study of climate are called climate elements. These are affected by climate factors, which determine a secondary variation at the local level.

The main climatic elements are:

Insolation is an element of fundamental importance as all the other atmospheric phenomena directly or indirectly depend on it: of the solar energy that reaches the atmosphere, a part (shorter radiation) is diffused by the clouds and by the molecules of the gases constituting 'air, a part is absorbed by water vapor and carbon dioxide, a part (long radiation) reaches the ground where it is absorbed and re-radiated into the atmosphere. The entity of the measurable insolation on the earth's surface during the day depends on the angle of incidence of the sun's rays and on the duration of the dм considerable influence is exerted by the cloudiness: the insolation, which theoretically decreases from the equator to the poles, has no its maximum at the equator, but in correspondence of the tropics where the transparency of the air is greater.

The distribution of temperature on the earth's surface is represented by the annual isotherms, lines that join all points of equal average annual temperature, reduced to sea level, they indicate that the temperature, following the trend of insolation, decreases from the equator to the poles: the hottest zone is not the equatorial one where the abundant vegetation and the high humidity cause the lowering of the average values, but a continental zone (thermal equator) shifted towards the Tropic of Cancer so the cold poles do not coincide with the geographic poles, but are displaced in the continental circumpolar regions. For climate studies, the temperature variations between the averages of the diurnal, monthly and annual maximums and minimums are also of great interest.

The pressure is important above all for the influence it exerts on many atmospheric phenomena such as winds, precipitation, convective air motions. It also has considerable importance for the so-called altitude climate, since the decrease in pressure with height does not affect only on some physical parameters (temperature, humidity, etc.) but it also has notable physiological effects on living organisms.

As for humidity, both absolute humidity and relative humidity can be considered from a climatic study. It is preferable to consider relative humidity, the variation of which causes significant effects also on organisms. The humidity varies continuously with evaporation and with atmospheric precipitations, the least humid regions are those far from the seas and devoid of vegetation. The humidity also decreases with the height, the absolute one very rapidly, while the relative humidity decreases slowly as the temperature decreases at the same time.

Precipitation is a climatic element, mainly dependent on the temperature and humidity of the air, widely used in climatic classifications. The monthly and annual totals of all rainfall are used, the frequency and intensity of rainfall, the monthly average values ​​and, in particular, the rainfall pattern, ie their monthly and seasonal distribution.

Cloudiness affects the temperature as it prevents much of the solar radiation from reaching the ground, on the other hand it retains the caloric radiations emitted by the ground preventing a strong night cooling and thus reducing the diurnal temperature range.

Climatic factors are called the conditions that produce variations on the elements of the climate. We distinguish zonal factors that act regularly from the equator to the poles and geographical factors that act differently for each locality. They are zonal factors: latitude, so from the equator to the poles the temperature decreases as the solar energy that the earth's surface receives decreases the general atmospheric circulation, which affects through the heat exchanges between the intertropical warm regions and the colder regions of the middle and high latitudes. Geographical factors are altitude, land and sea distribution, sea currents, vegetation and human activity. Altitude has great influence on the c. as the temperature, the pressure and the humidity decrease with the height, while the solar radiation and, up to a certain altitude, the rainfall increase. The arrangement of the reliefs is also very important: a mountain range transversal to the prevailing wind direction can cause heavy rainfall on the windward side and drought on the opposite side. For these reasons a particular climate has been defined, called mountain climate, characterized by strong diurnal and seasonal temperature variations, by notable local variations and by atmospheric instability. The distribution of lands and seas causes significant changes in temperature values ​​at different latitudes. The soil has poor thermal capacity and heats up quickly, but just as quickly it transfers the heat to the atmospheric layers the continents are therefore subject to significant temperature changes both daily and during the year on the contrary the sea, being able to transmit heat through convective motions, has a considerable thermal capacity and can therefore slowly release the heat received, attenuating the temperature fluctuations. We can therefore distinguish two climatic types: the continental and the maritime, the first is characterized by strong temperature variations, low humidity and limited rainfall, while the second is characterized by a certain uniformity between summer and winter, by weak excursions and by greater humidity and rainfall. The sea currents act on the climate of the coastal regions concerned: the hot currents make it constantly hot-humid, while the cold ones make it cold-humid. The vegetation, when it is very abundant, causes a decrease in temperature and an increase in humidity especially in correspondence with the hottest months. Human activity acts on the climate as it is capable of modifying the natural environment and the balance of ecosystems. In particular, atmospheric pollution, urbanization, modification of land use, intensive agriculture, the pushed industrialization of certain areas, etc., are all factors capable of modifying the climatic characteristics of more territorial areas. or less extensive and on a regional scale. The emission and accumulation in the atmosphere of certain chemical compounds capable of absorbing the terrestrial infrared radiation (greenhouse effect), such as carbon dioxide, methane, nitrous oxide, chlorinated and fluorinated hydrocarbons (such as freon), etc., on the other hand, they are factors capable of modifying the climate on a global level because they act on the overall energy balances of the atmosphere or modify the characteristics of the stratosphere and, in particular, of the ozonosphere. No less important factors on the medium and large scale climate are also some compounds of sulfur and nitrogen which, when chemically transforming in the atmosphere, give rise to the phenomenon known as "acid precipitation" or to the acidification of hydrometeors.

WINDS AND CLIMATE OF THE ISLAND OF ELBA

The climate of Elba is the classic maritime one with very mild temperatures even in winter. Rainy days are on average quite scarce, particularly in the summer months.

The prevailing wind is the sirocco (south-east) which hardly blows strongly, during the summer it alternates in the afternoon with the cooler mistral (north-west), which helps to make the days spent in the countryside less sultry and more pleasant. sea. On the contrary, the libeccio (south-west) and the west (west), although less frequent winds, when they blow they make themselves felt, shaking the sea considerably.

Particularly non-existent, if not in some sporadic winter days, the icy winds of the north (north) and grecale (north-east), in any case, thanks to the particular conformation of the coasts, the island always offers a point sheltered from any wind that may rage.


Temperature, thermal demands of plants, damage from high and low temperatures

The temperature regulates many functions of the plant, therefore it affects its development in a specific area. The germination of the seed, the germination of the buds, the flowering, the photosynthesis, are all functions regulated by the temperature, sometimes with the help of light.
For each species, there are maximum and minimum limits of bearable temperatures, called critical temperatures between these are the optimal temperatures, at which the plant grows regularly.
The influence of temperature on buds and seeds does not only concern their external development, but also affects their internal "maturation", which is conditioned by a period of low temperatures called the need for cold if this phase is lacking the organs they are in some way damaged and their development is certainly compromised.


Temperature - The temperature distribution on the earth's surface is represented by the annual isotherms, lines that join all the points of equal average annual temperature, reduced to sea level, they indicate that the temperature, following the trend of insolation, decreases from the equator at the poles: the hottest zone, however, is not the equatorial one where the abundant vegetation and high humidity cause the lowering of the average values, but a continental zone (thermal equator) shifted towards the Tropic of Cancer so the cold poles do not coincide with the geographic poles, but are displaced in the continental circumpolar regions. For climate studies, the temperature variations between the averages of the diurnal, monthly and annual maximums and minimums are also of great interest.

The factors of the climate. Climatic factors are called conditions that produce variations on the elements of the climate, there are zonal factors that act regularly from the equator to the poles and geographical factors that act differently for each location.
They are zonal factors:
1. the latitude, so from the equator to the poles the temperature decreases as the solar energy that the earth's surface receives decreases
2. the general atmospheric circulation, which affects through heat exchanges between warm intertropical regions and colder regions of medium and high latitudes.
They are geographical factors:
1. the altitude
2. the distribution of lands and seas
3. sea currents
4. the vegetation
5. human activity.
1. Thealtitude has great influence on climate since with height the temperature, pressure and humidity decrease, while the solar radiation and, up to a certain altitude, the rainfall increase. The arrangement of the reliefs is also very important: a mountain range transversal to the prevailing wind direction can cause heavy rainfall on the windward side and drought on the opposite side. For these reasons a particular climate has been defined, he said mountain climate, characterized by strong diurnal and seasonal thermal excursions, by notable local variations and by atmospheric instability.
2. The distribution of lands and seas causes significant changes in temperature values ​​at different latitudes. The soil has poor thermal capacity and heats up quickly, but just as quickly transfers the heat to the atmospheric layers the continents are therefore subject to significant temperature changes both daily and during the year on the contrary the sea, being able to transmit heat through convective motions, has a considerable heat capacity and can therefore slowly release the heat received, attenuating temperature fluctuations. They can therefore be distinguished two climatic types: the continental and the maritime the first is characterized by strong temperature variations, low humidity and limited rainfall, while the second is characterized by a certain uniformity between summer and winter, weak excursions and greater humidity and rainfall.
3. The sea ​​currents act on climate of the coastal regions concerned: the hot currents make it constantly hot-humid, while the cold ones make it cold-humid.
4. The vegetation, when it is very abundant, it causes a decrease in temperature and an increase in humidity especially during the hottest months.
5. Thehuman activity affects the climate as capable of modifying the natural environment and the balance of ecosystems. In particular, thepollution atmospheric, L'urbanization, the modification of land use, intensive agriculture, the pushed industrialization of certain areas, etc., are all factors capable of modifying the climatic characteristics of more or less extensive territorial areas and on a regional scale.


TEMPERATURE / here are the factors that influence it

The temperature The temperature and the main factors that influence it we will try to do it briefly, in order to offer a simple but at the same time comprehensive explanation.

TEMPERATURE, WHAT IS IT - Temperature is a physical quantity that indicates the thermal state of a body or a system, however there are some factors that can influence it in some way.

THE FACTORS THAT AFFECT TEMPERATURE - The main ones are: latitude, altitude, proximity to the sea, presence of winds and sea currents, orography and vegetation.

Latitude: different places in the world receive different quantities of solar rays, due to the astronomical motions of the earth and the inclination of its axis, the greater the inclination of the rays with respect to the earth's surface, the lower the energy absorbed.

The altitude
: since the warming of the atmosphere it mainly depends on the heat emitted from the surface of the earth, rising in altitude the temperature decreases.

Proximity from the sea: the sea surface has a much higher thermal capacity than the earth's crust: in summer the sea absorbs more energy than it emits, and vice versa, in the cold season it emits more energy than it receives.

Winds and sea currents: the circulation of air and water allows a great distribution of energy.

Orography
: mountain ranges act as an obstacle to the free circulation of air just think of the Alps, and how much in winter they act as an almost impassable barrier to the cold arctic currents.

Vegetation: woods and forests represent a temperature regulation factor: how water reduces temperature changes.

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