Weather

As weather (v. Althochdt. : Wetar = wind, labor) refers to tangible, short-term state of the atmosphere (also: measurable state of the troposphere ) at a specific location of the earth's surface , which among other things as sunshine , clouds , rain , wind , Heat or cold occurs.

The Meteorology classifies the local weather a certain time based on the various phenomena in the troposphere , the lower part of the atmosphere. The course of the weather determined by solar radiation and regional energy balance embossed atmospheric circulation .

Physically, weather can be described by thermodynamic state variables such as pressure , temperature and density . A “weather” in this sense can also be generated in a laboratory. In addition, there are such conditions and weather phenomena (for example winds) on other planets that have an atmosphere .

Definition of terms

The weather characterizes the state of the atmosphere at a certain place and at a certain time. Characteristic are the meteorological elements radiation, air pressure, air temperature, air humidity and wind, as well as the derived elements cloud, precipitation, visibility, etc. The weather is the momentary picture of a process (weather events) that mainly takes place in the troposphere . In contrast to the weather and weather conditions, it can change several times a day.

Weather situation : State of the atmosphere in a larger area and at a specific point in time. The weather situation changes more or less strongly from day to day.
Weather : The general, average or also predominant character of the weather at a location over a period of several days or weeks. Sensible weather elements such as precipitation, temperature, wind and humidity are particularly taken into account.
Climate : Thetypical annual weather patternfor a region (or a larger climatic zone ), for example mild, harsh or winter-humid climate. Describe in detail the monthly curves of temperature and precipitation, which result from weather statistics from many years to decades. The most important climate parameters include the solar constant , radiation balance , sensible and latent heat flows, heat flows in the oceans, general circulation of the atmosphere , and large volcanic eruptions .

Climate change : a long-term, profound change in larger areas or climatic zones. So is global warming in Siberia and in the Sahel is expected a significant impact (thawing of permafrost floors, each increasing drought), in Central Europe probably not.

A weather change is a - relatively rapid or sudden (within minutes to hours) - change in the weather situation in a certain area.

The weather can be viewed as a system that is primarily shaped by the elements temperature, precipitation, cloud cover, wind and air pressure. Some of the elements are related ( correlation or causality ), while others are not.

Weather in meteorology and colloquial language

Sky over the port of Tallinn (Estonia) on June 29, 2005 at 3 p.m.

The meteorologists record the individual elements of the weather with measuring devices and the weather situation using terms such as stable or changeable, bright or cloud-free , 3/8 cloudy, overcast or cloudy, fog tendency , rainy, rain shower or stormy.

Colloquially, very vague terms are common:

“Good weather” usually means sunshine - it is bad for a farmer , for example , whose seeds are supposed to sprout.
For Central Europeans , “cold weather” means - depending on the season - temperatures below −5 ° C or below around 15 ° C in midsummer.
In "hot weather" the ideas fluctuate less (from around 30 ° C), while "warm" is very relative.
What “ stormy ” weather is depends on the experience at the place of residence, on the orientation of the roads and generally on the terrain , possibly also on the effects on traffic or the practice of a sport .
“ April weather ” stands for “capricious”, changeable weather with a rapid succession of sun, clouds and showers .
In both scientific and general usage, a “calm weather situation” is a weather situation that is stable for days (“ high pressure situation ”) with little or even, weak wind .
“ Smog ” in large cities is a result of inversion weather conditions : A cold layer of air lies beneath a warmer one and thus prevents mixing (stable stratification of the atmosphere ). In the colder layer of air, dust, soot and exhaust gases from the city collect.

Elements of the weather and their measurement

The Meteorology studies the weather, quantifies its individual elements and characterized through a series of fundamental and special sizes (weather elements):

Air temperature
- temporal course
  - short term: drop in temperature
  - medium-term or seasonal: cold wave , heat wave
- Temperature extremes ( temperature minimum , temperature maximum )
- vertical gradient (average −0.6 K per 100 m)
Humidity and dew point
- Condensation level (the height at which the air temperature equals the dew point - this is where the cloud base is)
Air pressure and air pressure tendency
- High and low pressure areas
Winch and wind systems
- Wind direction or main wind direction and wind strength

atmospheric dynamics and energy balance

Turbulence , scintillation , etc.

Types of precipitation

Precipitation amount , water equivalent

Cloudiness (usually in eighths or tenths)

Cloud type (cumulus, cumulonimbus, alto-, cirrostratus, cirrus etc.)

Visibility (see airport or sea weather services )

vertical view, ground view , horizontal view

Mist and mist

Special appearances

Thunderstorm in the Kalahari near Stampriet , Namibia

Thunderstorms , thunderstorms , snowstorms
Fata morgana , halo , side sun
Rainbow , fog , weather lights (see atmospheric optics )
Cyclone , hurricane , tornado , cyclone
Sandstorm , Calima

These basic quantities are measured in weather stations , on weather ships and lighthouses , with weather balloons or radiosondes , with airplanes and buoys . Weather satellites , other earth observation satellites and spy satellites (the latter provide weather information as a 'by-product') observe the troposphere from space and collect a particularly large amount of information on cloud cover (also on large-scale cloud systems), wave heights and water surface temperatures in seas and air currents.

Mood of Wartau , Switzerland

Measuring instruments that serve to measure weather elements are called weather measuring devices (see also weather station , weather house ) or what they measure (e.g. anemometer , rain gauge , hygrometer , thermometer ).

Weather factors and their dynamics

The weather takes place almost exclusively in the lower 10 kilometers of the earth's atmosphere , the troposphere . Only here are there noticeable clouds because the water vapor, as a decisive factor, cannot get beyond the tropopause (about 8 to 15 km high, depending on the location and the season).

The weather is predominantly shaped by the lower 2 km of the peplosphere . Here there is often haze due to the accumulation of aerosols , and the nightly cooling due to thermal radiation. The ground friction slows the geostrophic wind , which is why it blows more in the direction of lower pressure than at higher altitudes.

The primary motor of the weather is the energy radiation from the sun and the radiation ( light and infrared ) to the clouds or into space . Today, in addition to terrestrial measurements, this is also recorded well by satellites and weather ships, radiosondes and other modern methods.

For the course of the weather, however, the flow conditions in the atmosphere are decisive, which depend on its changing humidity and the global wind systems , also on the regionally different heat reflection of the earth's surface ( albedo ), the terrain (especially the mountains , coasts and deserts) and from strong local influences (cyclical winds , inclination and vegetation on mountain slopes ...), and from the resistance to winds, which is determined by the roughness of the surface (forests, wind gaps , large buildings , etc.).

Therefore, in Central Europe, locally exact weather forecasts are only possible if all these details are accessible to modeling or reliable experience . The latter also know how to use lay people - see the proven Bauernregeln with "weather displayed" Bergen ( Wetterstein , Selva, etc.) or typical cloud formations as good weather - and fleecy clouds, fog , rain and scraps of clouds, cirrus , Föhnmauern etc.

Weather forecast

Main article: Weather forecast

Based on the weather recorded by large-scale measurements and thus the state of the atmosphere, weather models are used in meteorology to forecast the further development of the weather. Apart from that, however, it is also possible to make good predictions at the local level and with comparatively few resources, but this also requires more or less extensive knowledge.

Weather as an economic factor

For a number of companies, the weather has an impact on operational performance indicators. Classic examples of this are agriculture and the beverage industry , where weather can have a major impact on sales. While the harvest volumes are mainly affected in agriculture, sales of bottlers of mineral water and soft drinks fluctuate depending on the temperature. Other industries that weather can have a significant impact on include construction and tourism and leisure . For some companies, the weather risk can be so significant that it is specifically monitored in the company's risk management and, for example, hedged using so-called weather derivatives .

In 2012, the Cottbus regional court judged the weather as force majeure . Accordingly, bad weather is not at the expense of the client; it does not belong to the risk sphere of a buyer of construction work.

Influence of the weather on the course of wars

The weather situation plays an important role in many armed conflicts. Examples:

In weather with good visibility, an attacker can exercise his air superiority or air supremacy better than with low clouds. This played a role in the Allied advance in the winter of 1944/45: This winter was extremely cold and rainy.

In stormy seas or high waves, amphibious warfare is more difficult or even impossible. For example, in June 1944, during Operation Neptune , the first part of the Allied landings in Normandy , many amphibious tanks ran into water and sank before they could hit shore.

Frozen waters - especially rivers - can make attacks easier, make ports unusable and lock in ships anchored there. In the winter of 1944/45, frozen waters made it easier for civilians to flee from East Prussia, Silesia and other areas west of the Red Army (see displaced persons ).

Since the early 1950s, the military has also been researching ways to influence the weather locally. However, using such techniques would be a violation of the ENMOD convention .

Individual evidence

↑ Az. 6 O 68/11

literature

For general meteorological literature see Meteorology .

Richard Hennig : Good and bad weather , BG Teubner publishing house, Leipzig 1911.
Jörg Kachelmann , Siegfried Schöpfer : How will the weather be? An easy to understand introduction for everyone . Rowohlt, Reinbek bei Hamburg 2004, ISBN 3-498-06377-4 .
Jan Klage, Florian Mitgutsch (Illustrator): Weather makes history. The Influence of Weather on the Course of History . FAZ book, Frankfurt am Main 2002, ISBN 3-89843-097-9 .
Karl-Heinz Schirmer et al .: How does it work? Weather and climate . Meyers Lexikonverlag, Mannheim / Vienna / Zurich 1989, ISBN 3-411-02382-1 .
Verena Burhenne, Monika Weyer, Rosa Rosinski (eds.): Weather: bewitched, interpreted, explored. Catalog for the traveling exhibition of the same name by the Westphalian Museum Office (LWL) in collaboration with the Bielefeld Farmhouse Museum . Westfälisches Museumsamt, Münster 2006, ISBN 3-927204-64-1 .
Marie-Luise Heckmann : War and Weather - in narrative sources from Prussia and Livonia in the 13th and 14th centuries , in: Piśmienność pragmatyczna, edytorstwo źródeł historycznych, archiwistika. Studia ofiarowane Profesorowi Januszowi Tandeckiemu w sześćdziesiąta oiąta rocznicę urodzin , ed. by Roman Czaja and Krzysztof Kopiński , Toruń 2015, pp. 191–212.