Main printing area
The main pressure area , also called the standard pressure area , is the name given to some areas of equal air pressure in the atmosphere ( isobaric atmospheric geopotential heights ) .
Pressure areas in geopotential
The geopotential is the potential of the earth's gravitational field, i.e. the potential energy of a certain air parcel at a defined height in the atmosphere. It is characterized by gravity anomalies and corresponds to the height above sea level of the geoid ( geopotential height ). The amount is stated in geopotential meters gpm (or geopotential Deka meters gpdm respectively geopotential units GPU), its physical dimension is m ² / s ² or J / kg .
Areas of equal potential ( equipotential areas ) would correspond in the standard atmosphere to the atmospheric pressure at this altitude according to the barometric altitude formula . In reality, the areas of the same pressure ( isobaric areas) vary more or less around the standard values due to the temperature and pressure distribution:
- in high pressure areas the pressure surface sinks
- it rises in low pressure areas .
This corresponds to the fact that a pressure-based altimeter must be set according to the local air pressure in order to display the correct altitude. The pressure surfaces represent an (absolute) topography of the structures in the free atmosphere; the topography is given in hectopascals (hPa). The relative topography (RETOP) is then the mapping of the actual local conditions depending on the general weather situation and local weather .
For the purposes of aviation and recreational aviation ( aviation weather maps ), a modified representation is also used, namely isohypses (height-level lines), i.e. lines with the same deviation from the standard equipotential area or between two such in meters. These give a more direct statement about the display of the height measuring device in relation to its pre-calibration at the launch site. Typically, the isohypse map is based on sea level or a good 5000 m and shows deviations in the range of a few dozen meters plus / minus in the first case, a few hundred meters in the second.
Main pressure areas
According to the recommendation of the International Civil Aviation Organization (ICAO), main pressure areas are shown for some special pressures. They are also used in meteorology and atmospheric research because they make standardized statements about weather elements and atmospheric processes.
Specific application of individual pressure areas:
| Standard pressure area in hPa | Mean altitude in gpm | Height range in m | layer | Average temperature in ° C | Application in synoptics |
|---|---|---|---|---|---|
| 1000 | 111 | Lower troposphere | 14.3 | Ground pressure ; ∗ Fronts (temperature without daily variation) | |
| 925 | 764 | 10.1 | Temperature , deep cloud cover , wind | ||
| 850 | 1457 | around 1500 | 5.5 | Temperature , wind , deep clouds | |
| 700 | 3012 | 2800-3300 | Free atmosphere (upper troposphere) | −4.6 | Moisture , precipitation , uplift |
| 500 | 5574 | 5300-5800 | −21.2 | Dynamics , lift , waves | |
| 300 | 9164 | −44.6 | Planetary waves , jet stream | ||
| 200 | 11784 | −56.5 | Planetary waves |
- ∗ The standard air pressure at sea level is 1013.25 hPa.
use
The most important parameters of the (main) pressure areas are
- the anomaly , i.e. the height difference between standard pressure and geopotential surfaces
- the relative topography (retop), i.e. the difference between two standard pressure areas
- the isohypses , i.e. the contour lines of the atmospheric topography as shown in weather maps .
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Altitude weather map with isobars of the 500/1000 hPa retop and markings of the thermal wind of the pressure surface.
(Sample, DWD ) |
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Trough and bridge diagram: Hovmöller diagram of the 500 hPa altitude anomaly (5-day moving average over 45 ° N – 60 ° N, mean latitudes ), color-coded, plotted over time (3 months) and geographical longitude ( 180 ° O to 180 ° W); the diagram shows westerly wind drift (uniform rightward trend with time) and blockages (local breakdown of the same), as well as the intensity of the weather events.
( CPC-NCEP-NOAA ) |
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Action centers : animation of the 200 hPa altitude anomaly (world map, 5-day moving average); Dec. 6, 2013–5. Jan. 2014; the example shows a cold spell in North America and an explosive Siberia high .
( CPC-NCEP-NOAA ) |
|
300 hPa winds at altitude (average June 28 to July 4, 2015 , color-coded wind speed up to 100 kt); the example shows an omega position .
( NWS-NOAA ) |
Web links
- Archive of the reanalyses of the NCEP model (various main printing areas), on meteociel.fr (French) - from 1871 (as of 2017).
- Main printing area. In: Spectrum Academic Publishing House: Lexicon of Geography (2001, on Spektrum.de).
- Standard print areas. In: DWD: Wetterlexikon (on dwd.de).
proof
- ↑ a b c Relative and Absolute Topography - Significance and Use in Forecasting, Felix Welzenbach on Wetterzentrale.de, March 6, 2007.
- ↑ Relative and Absolute Topography - Significance and Use in Forecasting, Felix Welzenbach on Wetterzentrale.de, March 6, 2007.
- ↑ a b Isohypse. In: wetteronline.de → Wetterlexikon - with a map example .
- ↑ The geopotential: main pressure areas. ( Memento of the original from July 14, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. In: Denny Karran: World of Synoptics ( synoptische-meteorologie.de ).
- ↑ Meteorológiai kis-BETA. OMSZ Ismeret-Tár> Meteorológiai alapismeretek (Hungarian Weather Service: 'Basics of Meteorology> Weather Dictionary').
- ↑ 850 hPa temperature map. In: Denny Karran: Welt der Synoptik ( synoptische-meteorologie.de ), accessed July 27, 2017.
- ↑ 700 hPa relative humidity. In: Denny Karran: Welt der Synoptik ( synoptische-meteorologie.de ), accessed July 27, 2017.
- ↑ 500 hPa geopotential map. In: Denny Karran: Welt der Synoptik ( synoptische-meteorologie.de ), accessed July 27, 2017.
