Weather map

A weather map in a general sense is a map that makes the weather conditions over a geographical area at a certain time visually detectable. The time can be up to date, are in the past or in the future be (weather forecast).

From a meteorological point of view, it refers especially to the moment condition of the air pressure conditions over a wider area. Such a weather map provides information on the wind speed and wind direction or makes possible weather hazards early detection. It also allows a prediction of the coming weather. It can be used in everyday life meaningful.

As the inventor of the weather map applies the French scientist Urbain Le Verrier, who created a forecast map for France for the first time on 19 February 1855.

Surface weather maps

Emergence of a weather map

This provides a simple weather map can be created, first must be the air pressure readings of all weather stations in the catchment area of ​​the map. Consequently, all available data are entered by geographical order in the now empty card.

In the next step, the so-called isobars, ie lines of equal air pressure located. First, the highest air pressure value is searched and noted with an H for high pressure area on the map. Equivalently, the place of the lowest pressure value is determined and with T for low-pressure area marked (also L for Low). The isobars are then to high - and low-pressure area located: If site A has an air pressure of 1002 hPa and 1008 hPa place B, then there is the isobar of 1005 hPa approximately in the middle of the two places. The distances between the isobars be on German weather maps generally five hPa. Finally, you can judge by the size of the low and high pressure systems, the pressure conditions and the arrangement of isobars wind conditions.

Simple weather maps features at a glance

In addition to the isobars on a weather map are still more details, here are the most important:

For more weather maps

More detailed weather maps have other information about the current weather patterns. They contain data on temperature, wind speed, wind direction, air pressure changes, precipitation, cloud type, cloud cover, cloud base, dew point ( humidity) and the current weather.

To this end, this data is inserted into a specific pattern in the weather map with. The position of the data on the weather map marks the current position of the weather station. Only the most important stations are inserted with their data. Otherwise, the map would be too cluttered with weather data and no details visible.

Wind speed, cloud cover and air pressure tendency

Weather

Wind and pressure field

The wind is the movement of air and thus a mass flow. It results from the imbalance between two air masses of different temperature and pressure.

The Gradientkraft controls the air flows from high pressure to low pressure. Your direction is subject to a deviation in the direction of movement to the right in the northern hemisphere and to the left in the Southern Hemisphere due to the Coriolis force. The winds extend approximately isobarenparallel. This also allows the approximate wind direction can be determined.

The wind speed is dependent on the spacing of the isobars. If the isobars very close together, so a storm or even a hurricane can occur. We speak of a convergence, if the lines run close to each other. The isobars are separated by strong, like it happens in some high pressure weather conditions, it remains weak wind or no wind at all. This is called a divergence.

The following table gives an approximate indication of the wind speeds depending on the distance of the isobars, but here is a key function of the latitude:

Weather maps on German television

• For weather maps on TV and newspapers, it is common to emphasize the transmission or distribution area graphically. So is colored differently from the neighboring countries in the weather maps in the First Germany, in the maps of the WDR North Rhine-Westphalia is bordered sharp.
• In the two major television stations ( First and ZDF) is the graphical highlighting Germany's usual only since reunification in 1990. Previously, a Central European card came in both the " evening news " and in the "today" without limits for use.
• Despite the division of Germany the weather for both German states was predicted in the weather reports of the first and ZDF, which most notably by a " pan- German " Using weather symbols was expressed. While were drawn in the Weather Map of First some West German cities and Berlin, was on the ZDF card also find Leipzig. The term GDR was not used, instead it was " in the East", analogous to " the north " or " south-west " for regions in the former Federal Republic.
• Until the 60s, the news Germany was shown in the 1937 borders on the weather map.
• After the parliamentary resolution of the reunification first introduced the " evening news " a weather map showing the clearly defined area of the reunified Germany.
• The Germany Weather Map of the 20 - clock - " evening news " contained on March 30, 2008, the following cities: Kiel, Hamburg, Hannover, Cologne, Frankfurt, Stuttgart, Munich, Rostock, Berlin and Dresden. In the 19- clock - " today " card there were almost the same, instead of Hannover, Cologne and Frankfurt, however, Kassel, Bonn and Saarbrücken ( in other "today" spending is a more detailed map with other cities appear ).

Height weather maps

In all previous sections dealt with surface weather maps which the air pressure from measurements on the ground is based. The so-called altitude weather maps are determined with the aid of data from radiosondes. Height weather maps bring the indispensable complement in relation to what is happening in the free atmosphere, particularly with regard to the pressure and flow field at these altitudes. Interferences through mountains, cities and other obstacles are missing here and so have the contour lines ( contour lines of a certain air pressure area) usually looks smoother than the isobars of surface weather map.

The image of the height map weather can be quite different than that of the surface weather map. The development of low pressure areas on the ground shows that the development in height only gradually responding to the weather patterns on the ground.

In assessing the amount of weather maps so-called height lows play a major role with often extreme cold air inclusions (cold air drops). Low temperatures in the height solve, especially in summer at the same time warm the lower atmosphere from unstable weather conditions ( rain, heavy rain ).

The following heights Weather cards are most commonly used: