Weather station

A weather station is a compilation of various gauges that are used to measure meteorological parameters and thus the weather or air observation at a particular location.

Weather stations for State weather readings and forecasts - used other weather services and private purposes - such as the German Weather Service (DWD ). A distinction is generally between analog and digital weather stations.

The German Weather Service operates 111 full automatic weather stations (excluding staff). In contrast, the 70 weather stations of the DWD are staffed stations that perform much more extensive readings for weather observations.

• 2.1 Simple Weather forecast
• 2.2 Sensor Connection
• 2.3 Advantages of digital stations
• 2.4 disadvantages

Analog Weather Stations

Analogue weather stations are often in so-called weather cabins (including cabin thermometer, air hut) accommodated. These are small " boxes " made of wood or weather- resistant plastics that protect weather instruments from rain and dirt, but the same time ensure correct readings.

The simple, offered in department stores " weather stations " hardly worthy of the name. They are designed for indoor use only as a rule and its thermometer and hygrometer have display error of up to 3 ° C air temperature and 20 % relative humidity.

Weather huts and instruments

The above weather huts (also air cabins or huts called English ) consist of wind-permeable slatted walls and exterior painted white so as not to distort the temperature data by the sunlight. A dark surface would absorb in the sunshine, but even with a few clouds, more radiation to pass into the air and thus to indoor - outdoor temperature increase. Thus dark weather huts would always record too high a temperature and the systematic error would also vary depending on the weather development (see radiation error). Thus, the data from different weather stations are comparable, we have determined that weather huts exactly 2 meters above a grass surface and at least 10 meters from the nearest tree must be placed away, also the huts should be all day shone in the ideal case of the sun and made ​​freely by the wind. As an alternative to the conventional weather huts for automatic or digital stations ( see below) and smaller radiation shelters with active ventilation ( forced ventilation ) was used. Also, these are made of slatted walls, but are also equipped with a power-driven fan, so do not lead to a lesser extent of the housing by heating of the material to a corruption of the air temperature.

The " typical weather shelter " is equipped with a psychrometer, maximum and minimum thermometer and a Thermohygrograph.

Outside the weather shelter a rain gauge in the open air, a anemoscope and an anemometer is also attached. Some stations to measure in addition, the global radiation, sunshine duration or particular values ​​, such as evaporation or the floor temperature.

In order to collect data from these analog weather stations, the instruments must be read within the weather shelter. Outside the water level in the rain gauge and the current wind speed and direction is indicated on the anemometer. This is done by full-time stations every hour ( in addition to official stations only by 7, 14 and 21 clock ), the rain gauge every morning at 7 clock.

Advantages of analog stations

• No power source required
• Better assess how accurate and reliable are the current readings.
• Observer makes it even more visual observations ( eg weather history, visibility ), which are also very valuable and unmanned automatic weather stations omitted.

Disadvantages

• The weather data ( eg hourly ) recorded only at certain time intervals.
• The weather data must always be read "by hand", which entails a significant cost burden,.

Digital weather station

Digital weather stations have essentially the opposite advantages and disadvantages ( see below). They consist of two or more separate parts:

• The base station receives the data and evaluates
• The sensors for measuring data and the associated data transmission.

The sensors are attached to the desired measuring points where they collect and transmit data to the base station. This receives the data (either via cable or via radio ) and displays it on an LCD display. In addition, the data is usually stored for some time and may be recalled when needed.

More expensive stations transmit the data in a PC and / or also provide an approximate weather forecast for the next few hours.

For data interchange (EDI ) to a PC, different transmission paths are used. Most common are wired transmission paths through serial data cable, eg via RS232 / RS485 or dial-up connections via Analogue, ISDN or radio modems (GSM, GPRS). Increasingly, today's weather stations on the Internet Protocol -based data paths. This means that weather data via standardized protocols FTP, HTTP, SNMP in local area networks ( LAN) and wireless networks (WLAN), and worldwide on the internet. Modern weather stations also send SMS directly. ( Frost warning or current weather data on your mobile phone )

The sensors most commonly used are:

• Thermometer ( indoor and outdoor), hygrometer (often internal and external), barometer (mostly inside )
• Rain gauge and anemometer ( anemometer ) ( outside).

Some complex and costly systems offer more options as for cloudiness or radiation balance, and are equipped with webcams.

Simple weather forecast

With the help of air pressure build this digital weather stations, a weather forecast that predicts approached the coming weather. Such a forecast only because of the pressure tendency is usually very unreliable, since many of the factors responsible for the weather are not considered.

More modern stations at least consider even the course of the temperature, some even all data collected outside. Such forecasts are reliable and meet locally in 70 to 90 percent of cases, the correct prediction.

The official weather forecasts reach contrast, 80 to 90 percent, but also for larger regions as well as more accurate information including temperature, wind and rainfall. An experienced layman can locally ( only with wind and clouds) reach 70-80 % even without measurements, while the simplest - possible forecast " today as it was yesterday," after all, about 60% true.

Sensor connection

If the sensor data is transmitted via radio that happens mostly on the much used frequency 433 MHz of the 70 -centimeter band. Other radios that transmit also in this ISM band, can interfere with radio reception sensitivity. Newer models often use the frequency of 868 MHz and send bidirectional, to actively forden readings in real time.

Even when the radio transmission range is usually not very high, especially when several walls to penetrate. In addition to radio transmission, all sensors require a separate power supply; However, they can be created with low consumption with solar cells.

Cable -based systems have these problems, but then the cable must be long enough to reach to the sensors, and are also calibrated at higher claims.

Advantages of digital stations

• The data can be collected easily from the house, with many monotonous tasks eliminated and eliminating transmission errors by manual digitization or even a faulty reading of the measured values.
• Digitization and storage of the measured values ​​over a longer period of time automatically.
• It incurred lower maintenance costs, particularly through personnel savings.

Disadvantages

• Power supply is needed
• Incorrect data (eg by leaves or debris in the rain gauge, bird droppings on the global radiation sensor, etc. ) occur again and again and a manual review of the measuring apparatus is therefore often necessary as well as for analog weather stations
• Weather History is not observed in simple models