Weather

Power cumulus clouds

Common weather events on Earth are wind , clouds , precipitation ( rain , snow , hail , etc.), fogs , thunderstorms , dust storms and blizzards . Rarer events include natural disasters such as tornadoes and hurricanes . Almost all weather events occur in the troposphere (lower part of the atmosphere).

Differences in the physical properties of air masses arise due to changes in the angle of incidence of sunlight, depending on the latitude and remoteness of the region from the oceans. The large temperature difference between arctic and tropical air is a likely cause of high-altitude jet currents . Baric formations in mid-latitudes, such as extratropical cyclones , are formed, as a rule, as a result of the development of planetary waves in the zone of high-altitude jet flow. These formations, which have the main influence on weather changes as a result of instability of stream flows, (the so-called index cycle ) come in series. Since the axis of rotation of the Earth is inclined relative to the plane of its orbit, the angle of incidence of sunlight depends on the time of year. On average, the temperature on the Earth’s surface varies during the year within ± 40 ° C. Changing the parameters of the orbit, the angle of inclination of the axis and the angular velocity of the Earth’s rotation affects the amount and distribution of solar energy on the planet, being the main cause of long-term climate changes.

The difference in temperature on the surface of the earth in turn causes a difference in the atmospheric pressure field. A hot surface heats the air above it, expands it, lowering the pressure and density of the air. The horizontal pressure gradient , acting in conjunction with the centrifugal force and the Coriolis force associated with the rotation of the Earth, creates a wind directed in the free atmosphere along the lines of equal pressure - isobar. The atmosphere is a complex system, so minor changes in one part of it can have a big impact on the system as a whole.

Precipitation

The clouds are made up of very small drops of water or ice crystals that are so small that they only slowly sink under the influence of gravity. As they increase in size and become harder they fall faster and out of the cloud drops rain or snow. In any cloud, water vapor is in a saturated state, that is, within the cloud contains the greatest possible amount of steam at a given temperature. If this were not the case, the drops that make up the cloud would evaporate and the cloud would melt. Precipitation falls from clouds, which are composed of a mixture of water droplets and ice crystals. Due to the property of ice to attract water to itself, crystals gradually grow and turn into snowflakes. This explains not only snow, but also rain. In the troposphere, the air temperature decreases with altitude and it is always frosty at an altitude of several kilometers. Therefore, almost every summer rain begins like snow, and only falling into the lower warm layers, the snowflakes melt and turn into raindrops. ^[2]

Air mass movements

The air is in continuous motion, especially due to the activity of cyclones and anticyclones.

The mass of air that moves from warmer areas to colder, its advent is an unexpected warming. Moreover, from contact with a colder earth's surface, the moving air mass from below is cooled and the layers of air adjacent to the earth may be even colder than the upper layers. The cooling of the warm air mass, proceeding from below, causes condensation of water vapor in the lowest layers of air, as a result clouds form and precipitation falls. These clouds are low, often fall to the ground and cause fogs. The lower layers of warm air mass are quite warm and there are no ice crystals. Therefore, they can not give heavy rainfall, only occasionally shallow, drizzling rain. Clouds of warm air mass cover the entire sky with an even cover (then they are called layered) or a slightly wavy layer (then they are called layered cumulus).

Cold air mass moves from colder regions to warmer ones and brings cooling. Moving to a warmer earth's surface, it is continuously heated from below. When heated, not only does condensation not occur, but already existing clouds and mists should evaporate, nevertheless, the sky does not become cloudless, just clouds form for completely different reasons. When heated, all bodies heat up and their density decreases, so when the lowest layer of air heats up and expands, it becomes lighter and, as it were, floats in the form of separate bubbles or jets and heavier cold air falls into its place. Air, like any gas, is heated during compression, and cooled during expansion. Atmospheric pressure decreases with height, so the air rises, expands and cools by 1 degree for every 100 m of ascent, and as a result, condensation and cloud formation begin at a certain height in it. The descending jets of air from heating are heated and not only nothing condenses in them, but even the remnants of the clouds falling into them evaporate. Therefore, clouds of cold air masses are piles of piled up in height with gaps between them. Such clouds are called cumulus or cumulonimbus. They never sink to the ground and do not turn into fogs, and, as a rule, do not cover the entire visible sky. In such clouds, ascending air flows carry water droplets along to those layers where ice crystals are always present, while the cloud loses the characteristic shape of “cauliflower” and the cloud turns into a cumulonimbus. From this point of cloud precipitation falls, although strong, but short-lived due to the small size of the cloud. Therefore, the weather of cold air masses is very unstable. ^[2]

Atmospheric Front

The border of contact of different air masses is called the atmospheric front. On synoptic maps, this border is a line that meteorologists call the "front line." The boundary between the warm and cold air mass is an almost horizontal surface, imperceptibly descending to the front line. Cold air is below this surface, and warm above. Since the air masses are constantly moving, the boundary between them is constantly shifting. An interesting feature: the front line necessarily passes through the center of the low-pressure region, and the front never passes through the centers of the high-pressure regions.

A warm front arises when moving forward a warm air mass and retreating a cold one. Warm air, as lighter, creeps into the cold. Due to the fact that the rise of air leads to its cooling, clouds form above the front surface. Warm air climbs up quite slowly, so the cloudiness of the warm front is an even veil of cirrostratus and highly stratus clouds, which has a width of several hundred meters and sometimes thousands of kilometers in length. The further the clouds are in front of the front line, the higher and thinner they are.

The cold front moves toward warm air. In this case, cold air creeps under the warm. The lower part of the cold front lags behind the upper due to friction on the earth's surface, so the front surface bulges forward. ^[2]

Atmospheric Vortices

The development and movement of cyclones and anticyclones leads to the transport of air masses over considerable distances and the corresponding non-periodic weather changes associated with a change in wind directions and speeds, with an increase or decrease in cloudiness and precipitation. In cyclones and anticyclones, the air moves in the direction of decreasing atmospheric pressure , deviating under the action of different forces: centrifugal , Coriolis , friction , etc. As a result, in cyclones the wind is directed to its center with counterclockwise rotation in the Northern Hemisphere and clockwise in the Southern , in anticyclones, on the contrary, from the center with opposite rotation.

Cyclone is an atmospheric whirlwind of a huge (from hundreds to 2-3 thousand kilometers) diameter with low atmospheric pressure in the center. Distinguish cyclones extratropical and tropical .

Tropical cyclones ( typhoons ) have special properties and occur much less frequently. They are formed in tropical latitudes (from 5 ° to 30 ° of each hemisphere) and have smaller sizes (hundreds, rarely more than a thousand kilometers), but larger baric gradients and wind speeds reaching hurricane . Such cyclones are characterized by the “ eye of the storm ” - the central region with a diameter of 20-30 km with relatively clear and calm weather. Around are powerful continuous clusters of cumulonimbus clouds with heavy rains. Tropical cyclones can in the course of their development turn into extratropical.

Extratropical cyclones form mainly on atmospheric fronts, most often located in subpolar regions, contributing to the most significant changes in the weather. The cyclones are characterized by cloudy and rainy weather; most of the precipitation in the temperate zone is associated with them. In the center of the extratropical cyclone, the most intense precipitation and the most dense cloud cover.

Anticyclone is an area of ​​high atmospheric pressure. Typically, the weather is clear or cloudy. ^{[3] [4] [5]}

Small-scale eddies ( tornadoes , blood clots, tornadoes ) are also important for the weather.

" Meteorology (from the Greek. Metéōros - uplifted, heavenly, metéōra - atmospheric and celestial phenomena and ... logic), the science of the atmosphere and the processes occurring in it." ^[6]

• atmospheric physics is the main branch of meteorology that studies physical phenomena and processes in the atmosphere.
• synoptic meteorology is the science of weather and methods for its prediction. Weather forecast - “a scientifically based assumption of upcoming changes in the weather, compiled on the basis of the analysis of the development of large-scale atmospheric processes” ^[7] .
• Atmospheric chemistry studies the chemical processes in the atmosphere.
• Dynamic meteorology studies atmospheric processes with theoretical methods of hydroaeromechanics.
• Biometeorology studies the influence of atmospheric factors on biological processes.

The World Meteorological Organization coordinates the activities of meteorological services of various countries. ^[6]

Meteorological information

Two types of meteorological information can be distinguished:

• primary information about current weather obtained as a result of meteorological observations.
• weather information in the form of various reports, weather maps , upper-air charts, vertical sections, cloud maps, etc.

The success of weather forecasts is largely dependent on the quality of the primary meteorological information.

The main consumers of meteorological information are aviation and the navy ( water transport ). Agriculture is also very dependent on weather conditions and climate. Productivity is greatly influenced by soil and air humidity, rainfall, light, and heat. At the end of the 19th century, an independent branch of meteorology was formed - agrometeorology . Climate information is widely used in the design and operation of various structures - buildings, airfields, railways, power lines, etc.

Organization of meteorological observations

In Russia there is an extensive network of meteorological stations (various categories with different observing programs), meteorological and hydrological posts. Observations performed by meteorological radars (spatial images of cloud layers and the intensity of precipitation and thunderstorms in a radius of up to 250 km from the location of the locator) and meteorological artificial Earth satellites (television images of clouds in different wavelength ranges, vertical profiles of temperature and humidity in air) play a significant role. atmosphere). Aerologic observations are carried out on a network of special aerological stations using radiosondes , sometimes using meteorological and geophysical rockets. Observations on the seas and oceans from specially equipped vessels.

The ground-based meteorological network in the USSR reached its maximum development by the mid-1980s. The crisis economic processes that began in the late 1980s caused a noticeable reduction in the meteorological network. From 1987 to 1989, the number of weather stations in the USSR decreased by 15%; at the beginning of 1995, the decrease in the number of weather stations in the Russian Federation was 22%. In the future, it is also possible to reduce weather stations due to the development of other methods of obtaining weather information (satellite and radar).

Weather maps

A synoptic map ( Greek συνοπτικός , "visible at the same time") is a geographical map on which the results of observations of many weather stations are plotted with conventional signs. Such a map gives a visual representation of the current state of the weather. При последовательном составлении карт выясняются направления движения воздушных масс, развитие циклонов, перемещение фронтов . Анализ синоптических карт позволяет предвидеть изменения погоды. Можно отследить изменения состояния атмосферы, в частности перемещение и эволюцию атмосферных возмущений, перемещение, трансформацию и взаимодействие воздушных масс и пр. С середины 20 века приземная синоптическая информация дополнена результатами аэрологических наблюдений , на основе которых регулярно строятся карты состояния свободной атмосферы — так называемые карты барической топографии. С конца 20 века широко используется также спутниковая информация о состоянии океанов и частей суши, где нет метеостанций. Фотографирование облачных систем со спутников позволяет обнаружить зарождение тропических циклонов над океанами.

Изучение погоды на других планетах

Weather exists not only on Earth, but also on other celestial bodies ( planets and their satellites ) that have an atmosphere. Studying the weather on other planets has become useful for understanding the principles of changing weather on Earth. A famous research object in the Solar System - Jupiter's Great Red Spot, is an anticyclonic storm that has existed for at least 300 years. However, the weather is not limited to planetary bodies. Crown of the Sun is constantly lost to space, creating, in essence, a very thin atmosphere throughout the Solar System. The movement of particles emitted by the Sun is called the solar wind .

• Atmospheric phenomena - visible manifestation of complex physical and chemical processes occurring in the air casing Earth - an atmosphere :
  • precipitation ( rain , snow , hail )
  • fog
  • blizzard
  • storm
  • tornado and t. d. ^[8]
• Values ​​defining " equivalent comfortable temperature ":
  • Atmosphere pressure
  • air temperature
  • air humidity
  • wind speed and direction
• Values ​​important for transport and agriculture:
  • range of visibility
  • atmospheric turbulence
  • possibility of icing
  • solar radiation
  • cloudiness , duration of sunshine
  • the possibility of a storm (at sea, large lake)

A weather forecast is a scientifically and technically sound assumption about the future state of the atmosphere in a particular place. People tried to predict the weather for millennia, but official forecasts appeared in the nineteenth century. To make a weather forecast, quantitative data about the current state of the atmosphere are collected, and with the help of a scientific understanding of atmospheric processes, it is projected how the state of the atmosphere will change.

If earlier forecasts were based mainly on changes in atmospheric pressure , current weather conditions and the state of the sky, now forecasting models are used to determine future weather. Human participation is necessary to select the most appropriate forecasting model, on which the forecast will be based in the future. This includes the ability to choose the model template, the account relationship remote events, knowledge of the principles of operation and features of the selected model. The complex nature of the atmosphere, the need for powerful computer technology to solve equations describing the atmosphere, the presence of errors in the measurement of initial conditions, and an incomplete understanding of atmospheric processes mean that the accuracy of the forecast is reduced. The greater the difference between the present time and the time for which the forecast is made (forecast range), the less accuracy. Using several models and bringing them to a single result helps to reduce the error and get the most likely result.

Many people use weather forecasts. Storm warnings are important predictions, as they are used to protect life and property. Forecasts of temperature and precipitation are important for agriculture and, therefore, even for stock market traders . Moreover, there are even so-called Derivative financial instruments for the weather. ^[9] Temperature forecasts are also needed for heating networks to estimate the thermal energy needed in the coming days. Every day, people use the weather forecast to decide what to wear on that day. Forecasts of rains, snow and strong winds are used for planning work and outdoor recreation.

Currently, there is a grid project ClimatePrediction.net , the purpose of which is to find the most appropriate model of climate change and build on its basis a forecast for the next 50 years.

Weather plays a big, and sometimes even decisive role in human history. In addition to climate changes that caused the gradual migration of peoples (for example, desertification of the Middle East and the formation of land bridges between the continents during the ice ages), extreme weather events caused smaller scale movements of peoples and were directly involved in historical events. One such case is the rescue of Japan by Kamikaze winds from the invasion of the Mongolian fleet by Khan Khubilai in 1281. The French claim to Florida ended in 1565 when a hurricane destroyed the French fleet, giving Spain the opportunity to conquer Fort Carolina. More recently, Hurricane Katrina has forced more than one million people to relocate from the central Gulf of Mexico to the United States, creating the largest diaspora in US history.

In addition to such a radical effect on people, the weather can affect a person in more simple ways. People do not tolerate extreme values ​​of temperature, humidity, pressure and wind. Weather also affects mood and sleep.

The desire to influence meteorological phenomena can be traced throughout the history of mankind: from the most ancient ritual ceremonies in an attempt to summon rain, to special military operations of our time, such as Operation Popeye of the American military during the Vietnam War (1965-1973), when Attempts were made to prevent the supply of weapons and food to the South Vietnamese partisans by extending the period of the Vietnamese monsoon . The most successful attempts to influence the weather include cloud sowing , active influence on fogs and layered clouds to disperse them, used by large airports, techniques to increase snowfall over mountains and reduce hailstorms ^[10] .

A fresh example of the impact on hydrometeorological processes is the measures taken by China for the 2008 Summer Olympic Games . 1104 missiles were launched, with the help of which they are sown in clouds of special reagents. Carried out over Beijing, they were intended to avoid rain during the opening ceremony of the Games on August 8. Hu Guo, head of the Beijing City Meteorological Bureau, confirmed the success of the operation. ^[eleven]

While the effectiveness of such methods of influencing the weather has not yet been conclusively proven, there is convincing evidence that agriculture and industry influence the weather ^[10] :

• Acid rain caused by the release of sulfur oxide and nitrogen oxides into the atmosphere adversely affects lakes, plants, and buildings.
• Human waste on the environment impairs air quality and visibility .
• The construction of cities, roads, deforestation, changing the landscape, leads to an increase in the albedo of the earth's surface. Impurities emitted into the atmosphere by industrial enterprises, settling on the Earth, also contribute to a decrease in the reflectivity of the Earth's surface (especially in winter). These factors affect the thermal balance of the atmosphere, contributing to climate change (warming) in cities and industrial regions.
• Climate change caused by processes leading to the release of greenhouse gases into the air is believed to affect the frequency of occurrence of such adverse events ( extreme weather ) as drought , extreme temperatures, floods , storm winds and storms ^[12] .
• The amount of heat produced by large urban conglomerates immediately affects the weather in the region even at distances of 1000 miles ^[13] .

The effects of unintentional changes in weather conditions can pose a serious threat to many components of our civilization, including ecosystems , natural resources , economic development, and human health ^[14] .

Micrometeorology , considering meteorological phenomena of small and ultra-small scales, both in time and in space, deals with atmospheric phenomena less than one kilometer, that is, those that are no longer considered medium-sized meteorology ( English Mesoscale meteorology ). These two branches of meteorology are sometimes combined together, and they include the study of objects whose scales are smaller than those considered by meteorology of synoptic scales ( English Synoptic scale meteorology ) and cannot be reflected on the synoptic map . This can include small and usually wandering clouds and similar objects ^[15] .

Studying the weather features on other planets contributes to a deeper understanding of the processes occurring on Earth ^[16] . On other planets, weather conditions are subject to many of the physical laws inherent in the weather on Earth, but they occur on different scales and in atmospheres that are different in chemical composition from the earth. The Cassini-Huygens mission to Titan discovered on a satellite clouds formed from methane or ethane that produce rain, consisting of liquid methane and other organic components ^[17] . The Earth’s atmosphere consists of six latitudinal circulation zones, three in each hemisphere ^[18] Unlike Earth, Jupiter is surrounded by many such zones ^[19] . Titanium has only one stream near the 50th parallel of north latitude ^[20] and one near the equator ^[21] .

Weather records are extreme meteorological indicators that have been officially recorded on the surface of the Earth. The lowest temperature in history was recorded on July 21, 1983 at Vostok Station , Antarctica −89.2 ° C. The highest recorded on September 13, 1922 in Alazizi, Libya . Then, the thermometer rose to +58 ° C; value however, is disputed.

• Climate
• dynamic meteorology
• Weather station
• Numerical weather forecast

• Mantashyan P.N. Cyclones and anticyclones // Science and Life. - 2008. - No. 3.

• The site of the Hydrometeorological Center of Russia - http://meteoinfo.ru
• Customizable interactive weather internet resource ventusky.com created by InMeteo , a Czech company.