Study of weather
Contenido
Hay muchas clases de tiempo: cálido o frío, húmedo o seco, despejado o tormentoso, las cuales resultan de diferentes combinaciones de las variables atmosféricas de temperatura, presión, viento, humedad y precipitación. El tiempo siempre ejerció poderosa influencia sobre las actividades humanas, y durante siglos el hombre ha estudiado la atmósfera, tratando de comprender su comportamiento.
La meteorología es la rama de la ciencia que estudia esta envoltura de aire en torno de nuestro planeta.
Las variaciones a corto plazo de la atmósfera (que llamamos tiempo meteorológico), se relacionan con nuestra vida cotidiana. La lluvia que riega nuestras cosechas y llena nuestros embalses es parte del tiempo, lo mismo que los huracanes y tornados que dañan nuestras ciudades y el rayo que puede fulminarnos en un segundo.
En un principio, los hombres simplemente observaban el tiempo; luego trataron de emplear sus observaciones como base para la predicción y anticipación de las condiciones meteorológicas; finalmente aprendieron que no podían pronosticarlas con mucho éxito sin comprender su funcionamiento. Y cuando finalmente se consiguió cierto conocimiento de los procesos atmosféricos, se comenzó a pensar en el intento de alterarlos. Estos son los tópicos que consideramos aquí: los esfuerzos humanos para observar, predecir, entender y aminorar los efectos negativos del tiempo atmosférico.
Elements of climate
The constituent elements of climate are: temperature, pressure, wind, humidity and precipitation. Having a record for many years of the values corresponding to these elements in a given place helps us to define what the climate of that place is like. Of these five elements, the most important are temperature and precipitation, because to a large extent, the other three elements or features of climate are closely related to the two that have been mentioned. This means that a higher or lower temperature gives rise to a lower or higher atmospheric pressure, respectively, since hot air has a lower density and therefore rises (cyclone or low pressure zone), while cold air has a higher density and has a tendency to descend (high pressure zone or anticyclone). In turn, these pressure differences give rise to winds (from anticyclones to cyclones), which transport humidity and clouds and, therefore, give rise to the distribution of rain over the Earth's surface.
It refers to the degree of specific heat of the air at a given place and time. The climate depends on the way in which the energy of solar radiation is distributed between the atmosphere and the Earth's surface. The climate is warmer where more energy reaches the surface, and colder where less.
This insolation depends on two types of factors:
• - Planetary factors: the Earth's rotation movement (which causes day and night, with the thermal differences that this entails) and the translational movement of the Earth around the Sun, which gives rise to the seasons (times of greater or lesser exposure to solar radiation due to the inclination of the Earth's axis with respect to the ecliptic or Earth's orbit).
Effect of solar angle on climate.
• - Geographical factors. They are those that depend on the specific conditions of the place with respect to the thermal characteristics of the air in said place. They are: latitude (which explains the greater or lesser solar radiation depending on the inclination of the Earth's axis throughout the year); altitude, which gives rise to the thermal differentiation of the atmosphere, giving rise to what is known as thermal floors, a fundamental aspect in the study of climate; the greater or lesser distance to the sea that affects the greater or lesser oscillation or thermal amplitude of the air, respectively; the orientation of the relief according to the insolation (sunny slopes or slopes, warmer, and shady "Umbria (geography)"), colder, both considered at an equivalent altitude and latitude) and the marine currents, which provide a very important way of transferring heat from the intertropical zone to the temperate and polar zones, making the climate in the latter geoastronomic zones milder.
These five factors not only affect atmospheric temperature, but also the rest of the elements of climate: atmospheric pressure, winds, humidity and precipitation.
It is the pressure exerted by the weight of air masses in all directions, and varies inversely with altitude and directly with temperature, that is, under normal conditions, the higher the altitude, the lower the temperature, the lower the pressure.
It is the movement of air masses according to differences in atmospheric pressure. In a general sense, the wind is the vehicle by which energy is transported within the atmosphere and, therefore, helps to distribute that energy more equitably. Wind is a fundamental element in the hydrological cycle which, in turn, is essential to sustain life on Earth.
Humidity is the water that permeates a body or the vapor present in the atmosphere. Water is present in all living bodies, whether animals or plants, and that presence is of great importance for life.
It is any form of hydrometeor from atmospheric water in the form of clouds that falls to the Earth's surface through different forms of precipitation (rain, snow, hail, etc.).
Factors that determine the climate
• - Latitude.
• - Altitude.
• - Distance to the sea.
• - Ocean currents.
• - Orientation of the relief.
• - Direction of planetary and seasonal winds.
Geographic latitude
• - Effects on atmospheric temperature:.
Latitude determines the inclination with which the Sun's rays fall and the difference in the duration of day and night. The more directly the solar radiation hits, the more heat it contributes to the Earth.
The variations in insolation that the Earth's surface receives are due to rotation movements (daily variations) and translation (seasonal variations).
Variations in latitude are caused, in fact, by the tilt of the Earth's axis of rotation. The angle of incidence of the Sun's rays is not the same in summer as in winter, being the main cause of seasonal differences. When the sun's rays hit at a greater angle, they heat much less because the atmospheric heat has to be distributed over a much greater thickness of atmosphere, which filters and disperses part of that heat. This fact can easily be verified when we compare the insolation produced in the morning and afternoon hours (radiation with a greater inclination) with that we receive in the hours close to noon (more effective insolation due to its lower inclination). That is, a greater inclination of the sun's rays causes them to have to pass through a greater amount of atmosphere, becoming more attenuated than if they were more perpendicular. On the other hand, the greater the inclination, the greater the horizontal component of the radiation intensity. Through simple trigonometric calculations it can be seen that: I (incident) = I (total) • cosθ. Thus, the sun's rays hit with a greater inclination during winter, which is why they heat up less in this season. We can also refer to the daily variation in the inclination of the sun's rays: the coldest atmospheric temperatures occur at dawn and the highest temperatures occur in the afternoon.
• - Effects on precipitation:.
Latitude determines the location of the action centers that give rise to the winds: anticyclones (high pressure centers) and cyclones (low pressure areas or depressions). Anticyclones are areas of high pressure, where the air descends from a certain height because it is cold and dry (cold and dry air is heavier than warm and humid air), while cyclones are areas of low pressure where the air rises due to its lower density. The location of the major centers of action determines the direction and mechanics of the planetary or constant winds and, consequently, the areas of greater or lesser amounts of precipitation. The four notable parallels (Tropics and polar circles) generate the existence of large anticyclonic zones and depressions of dynamic origin, that is, caused by the movement of the Earth's rotation and of thermal origin (originated by the unequal distribution of atmospheric heating).
Relief altitude
The height of the relief substantially modifies the climate, especially in the intertropical zone, where it becomes the most important climate-modifying factor. This fact has determined a criterion for the conceptualization of thermal floors, which are climatic belts delimited by contour lines that also generate temperature curves (isotherms) that have been established taking into account types of vegetation, temperatures and orientation of the relief. The existence of four or five thermal floors in the intertropical zone is considered:
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- Macrothermal (less than 1 km high), with a temperature that varies between 27 °C at sea level and 20 °.
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- Mesothermal (1 to 3 km): it has a temperature between 10 and 20 °C, its climate is temperate mountain.
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- Microthermal (3 to 4.7 km): its temperature varies between 0 and 10 °C. It presents a type of moor or cold climate.
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- Frigid (more than 4.7 km): its temperature is less than 0 °C and a climate of perpetual snow corresponds to it.
Some authors subdivide the mesothermal floor into two to achieve greater precision because the difference in altitude and temperature between 1 and 3 km is too large to include a single climatic floor. This would leave an intermediate floor between 1000 and 1500 m that has been called subtropical floor, although this is a misnomer since this term refers to a specific latitude and not to a thermal floor determined by temperature. And the floor located between 1500 and 3000 m would constitute the temperate floor, which would be followed by the moor floor up to .
The approximate calculation made is that when rising 160 m, the temperature drops 1 °C. As can be seen in the main article on thermal floors, the decrease in temperature with altitude varies depending on the geoastronomic zones in which we find ourselves. If it is in the intertropical zone, in which the thickness of the atmosphere is much greater, the temperature drops by 1 °C, not at 160 m of ascent, but at approximately 180 m.
Relief orientation
The arrangement of the mountain ranges with respect to the incidence of solar rays determines two types of mountain slopes or slopes: sunny and shady "Umbria (geography)").
To the north of the Tropic of Cancer, the sunny slopes are those that face south, while to the south of the Tropic of Capricorn the sunny slopes are, obviously, those that face north. In the intertropical zone, the consequences of the orientation of the relief with respect to the incidence of solar rays are not so marked, since part of the year the sun is incident from north to south and the rest of the year in the opposite direction.
The orientation of the relief with respect to the incidence of the dominant winds (planetary winds) also determines the existence of two types of slopes: windward and leeward. It rains much more on the windward slopes because the relief gives rise to orographic rains, by forcing the rise of humid air masses.
Continentality
The proximity of the sea moderates extreme temperatures and usually provides more humidity in cases where the winds come from the sea towards the continent. Sea breezes attenuate heat during the day and land breezes limit nocturnal irradiation. In the intertropical zone, this breeze mechanism tempers the heat in coastal areas since they are stronger and more refreshing, precisely, the hotter it is (in the early afternoon).
High continentality, on the other hand, accentuates the thermal amplitude. It will cause cold winters and hot summers. The most notable example of climatic continentality is in Russia, especially in the central and eastern part of Siberia: Verkhoyansk and Oimyakon compete with each other as the poles of cold during the long boreal winters (less than 70 ° C below zero). Both populations are found relatively close to the Arctic Ocean and the Pacific Ocean in its northernmost part (north of the Arctic Circle), but very far from the western areas of the thermal equator of both the Atlantic and the Pacific Ocean, which is where the dominant moisture-laden winds (westerly winds) come from.
Continentality is the result of the high specific heat of water, which allows it to remain at colder temperatures in summer and warmer in winter. It is the same as saying that water is not diathermanous since it is heated directly by the sun's rays although it has great thermal inertia: it takes a long time to heat up, but it also takes longer to cool down by irradiation, compared to terrestrial or continental areas. Water masses are, therefore, the most important climate moderating agent.
ocean currents
Marine currents or, more appropriately, ocean currents, are responsible for transferring an enormous amount of water and, consequently, thermal energy (heat). The very powerful influence of the Gulf Stream, which brings warm waters from intertropical latitudes, makes the Atlantic coast of Europe more temperate than what would correspond to its latitude. On the other hand, other areas of the east coast of North America, located at the same latitude as those of Europe, have much lower temperatures, especially in winter. The case of Washington D.C., for example, can be compared to Seville, which is at the same latitude, but which has much warmer winters. And this difference is accentuated further north, because to the distance from the Gulf Stream we must add the influence of the cold waters of the Labrador Current: Oslo, Stockholm, Helsinki and Saint Petersburg, capitals of European countries, are located at the same latitude as the Labrador Peninsula and Hudson Bay, territories practically uninhabited due to the extremely cold climate. Another interesting example that temperatures do not have a strict correspondence with latitude, when it comes to cold or warm ocean currents, is found in the fact that the ocean waters in Spain and Portugal are warmer than on the coasts of the Canary Islands and Mauritania, despite the lower latitude of the African coasts, due to the fact that in both cases the effects of two different currents are influencing: the Gulf Stream on the European coasts and that of the Canary Islands. on the African coasts.
Cold currents also have a powerful influence on the climate. In the intertropical zone they produce a very arid climate on the western coasts of Africa and America, both north and south. These cold currents are not due to a polar origin of the waters (something that has been pointed out in some texts for a long time), which would not be explained in the case of the cold currents of California and the Canary Islands since both are located between warm currents at higher and lower latitudes. The coldness of the currents is due to the rise of deep waters on these western coasts of the Intertropical Zone. This slow but constant rise of the waters is very evident in the case of the Humboldt Current or Peru, an area very rich in plankton and fishing, precisely due to the rise of deep waters, which bring a large amount of organic matter to the surface. Since cold waters produce high atmospheric pressure, as explained in the articles on Venezuelan Guiana and on diathermancy, the relative humidity in cold water areas is very low and there is very little or no rainfall: the Atacama Desert is the driest in the world.
The reasons for the emergence of cold waters are due to two reasons related to the rotation movement of the Earth:
• - Firstly, to the direction of the planetary winds in the intertropical zone and to the direction of the equatorial currents. In both cases, that is, in the case of winds and marine currents, the movement occurs from east to west (in the opposite direction to the Earth's rotation) and away from the coast. In turn, this distance from the coast of the winds and surface waters creates the conditions that partly explain the rise of deeper waters, which come to replace the receding surface waters. Finally, in the intertropical zone, the winds are from the East, due to the rotation of the Earth, so on the western coasts of the continents in the intertropical zone they blow from the continent towards the ocean, so their humidity is very low. On a much smaller scale, this phenomenon can be seen on the Spanish Levantine beaches: when the west wind blows, the Mediterranean is without waves (ruffled, at best) but the waters on the beach feel much colder than normal. And in the case of the island of Margarita it is much more evident, because the easterly winds blow there all year round and at any time: the temperature of La Galera beach in Juan Griego is much colder, although without any perceptible waves, than that of Playa El Agua or Playa de El Tirano, on the eastern coasts of the island, located just about 15 km to the east.