Introduction

Modern weather station software is able to display weather data in a confusingly large number of text and graphic views. This page describes the more common viewing formats to illustrate their different features and to help when comparing viewing options offered by the available software packages. The descriptions focus mainly on local views, ie displays of data on the linked PC. Additional views may be possible by including weather data in web pages, for example, and making them available online.

One useful distinction in helping to understand the various data views is based on the age of the data being displayed. Defining three ages is helpful: current data is the very latest available set of values for the weather parameters being measured and is therefore gathered at a single point in time; recent data covers a span of time and denotes the set of data from a point in the recent past, eg 60 minutes or 24 hours ago, up to and including the latest data (ie the current data); past data also covers a span of time points but is a set of contiguous data with a specified start and end time, for example all of the data for February or the third week in July. Most of the time, weather displays will show current data with extra information being added by including recent data also. Only occasionally will there be a need to look at past data and the weather software will usually have a separate mode to inspect and to graph past data. 

Some illustrations are provided in the following notes wherever an icon can be seen. Click this for a larger view and use your browser back button to return here. Please use the set of links below to jump directly to a view of specific interest:

Current data

This is the most obvious and popular view of logged weather data when presented on  PC display. The current data view displays effectively a snapshot of current weather conditions and will be updated at least every few seconds on a PC actively linked to the weather station (Copies of the current data view on remote sites, eg web sites, may obviously show an older view according to when they were last updated). On more primitive software, the current weather values will be shown as text values only, but the better and more recent software (eg Weatherlink, Virtual Weather Station (VWS), Weather View 32 (WV32) etc) is capable of generating an impressive graphical display, using a range of colourful graphical devices beyond text and simple graphs, if desired. 

Traditionally, the current data view shows only the single most recently available value for each reported parameter, though it is customary to report a trend value (up/down/steady) for barometric pressure only. Indeed sometimes, as for example in the Bulletin mode of Weatherlink, the current view will display a full trend graph for the pressure parameter only. Often maximum and minimum values (measured since these limit values were last reset at eg midnight or 6AM daily) for the various weather parameters can also be included, either as text values or as markers on the graphical displays. Clearly, the inclusion of even a single trend graph is moving beyond the strict traditional definition of the current view, by including recent as well as current data. In fact this mixing of current and recent data to achieve a more informative primary display is a hallmark of the approach taken by modern weather software such as VWS and WV32. For this class of software, the current data view is not a relatively simple (though colourful) separate mode as is the case for Weatherlink and other more basic software, but part of a much more comprehensive display, better described as an integrated primary display and described next. 

Integrated primary displays

Both VWS and WV32 have a powerful mechanism for generating this impressive integrated primary display, which assembles individual graphic elements, each corresponding to a distinct representation of the state or value of a weather parameter, into an overall display screen. There is a whole range of individual elements, including text, trend graphs, working representations of weather instruments such as barometers and thermometers and special graphic components for specific weather parameters such as gauges to show wind direction and speed. Arbitrary graphic images can also be placed on this primary display screen. VWS has an especially rich set of graphic components and includes additional elements such as spectrum displays, pie charts etc., while WV32 has more character and visual appeal in certain of its special components.

In both VWS and WV32, these elements can be arranged on screen and their colour and size, to a large extent, varied at will to create an essentially infinite number of different arrangements whose overall final appearance is limited more by artistic considerations than any technical constraint. The view of current weather data is therefore an integral part of this overall primary display, but recent trend information and items of daily summary data (eg min and max values) are also included to enhance the the information content of this single overall screen. For VWS this main integrated display is the only screen environment where weather data is reported or analysed (other than two summary data panels). In the case of WV32 there is a separate configuration and analysis environment where previously logged data can be plotted in a powerful charting utility and where the primary database can be browsed and manipulated..

[NB In addition to acting as the primary display medium for weather data, the integrated display serves another important function in WV32. It forms the basis of the graphical image which is available for uploading to remote servers such as web servers. In VWS the integrated display is used to configure individual graphic elements, but not their mutual layout. VWS and WV32 take interestingly distinct approaches to the mechanism by which the images are merged to form, for example, a final web page. With VWS, each graphic element is saved and uploaded as a separate and uniquely named jpeg file. The elements are then reassembled according to the specified layout of the web page in which they are destined to appear. In contrast, WV32 saves the whole integrated display locally as a single large image which is then uploaded as a single entity and positioned at one spot in it target web page. There are pros and cons to both approaches.]

Web page views

How weather station software can incorporate data into web pages is a topic introduced elsewhere in the main OLAWS section and dealt with more specifically on the web data methods page. But some packages effectively have a mode where the web page can be used as a medium for local viewing of current weather and this needs to be mentioned here as a further model of data view. In some ways this is an attractive option because any amount of additional text and formatting can be added to the display of basic weather data to create an attractive, flexibly-laid out and well-labelled data view.

As explained in much more detail on the web data methods page, data can be included in web pages in two ways - as graphical images containing embedded data and as text fields updated via the placeholder technique. The web page can then be viewed locally using a standard web browser. If the weather package can create content for web pages using either of these two methods and it can perform purely local updating of the content then the web page view may be an excellent choice for the local weather display. Instructions for creating an automatically-updating local web page may be hidden away in the package and there may be certain technical considerations, for example, the mechanism by which automatic updating is achieved, but the result may repay a small  investigation and development effort.

Trend graphs

Visually, the second most useful display of weather data is the trend graph, which shows how the value of one or more weather parameters is changing with time. Use of the trend graph as a component of the integrated primary display in WV32 and VWS was noted above. Striking effects can often be seen if two or more trend graphs monitoring different weather parameters are stacked vertically with the time axes matched. Because of its visual value, a trend graph generator is often implemented as a distinct graphic tool in weather software, even though it is really just one case of the more general XY plot.

Thus the trend graph is often set up to reflect newly logged data automatically and updating minute by minute, at the expense of limiting several of the formatting options for the graph and restricting the plot to one parameter per trend graph.  In contrast, the general XY plot has much more formatting flexibility but is designed to be used interactively rather than automatically. This distinction is reflected in some packages in the source of data for the two types of plot. Thus trend graphs will use real-time data which may be unlogged, whereas the general XY plot will retrieve data from the primary database and will therefore display only data which has been already logged to the database, for example at the last archive download for Davis systems.

As an example, the trend graph mode of the Weatherlink software is called the Strip Chart. As usual with Weatherlink, the mode is more limited than the corresponding modes in VWS and WV32 and there is a fixed format of 4 stacked trend graphs. Any one of several parameters can be shown on each trend graph, but other than setting the time span of the plot, there is relatively little control possible over the appearance of the graphs. For example, the Y axis will always autoscale. 

The trend graphs in WV32 are set up and viewed through the integrated graphical display. Other than the fact that only one parameter per trend graph can be plotted, they are much more flexible than the Weatherlink equivalent and represent currently the best implementation of trend graphs in the three main packages. However, as with Weatherlink, inability to scale the Y axis manually remains a significant drawback.

With VWS has only one plotting mode which serves for both trend and more general plots.

General XY plots

This more general form of plotting facility is implemented in all three main packages (Weatherlink, WV32 and VWS), though in VWS it is a component of the integrated primary display rather than a quite separate plotting environment. To reiterate, the general XY plotting tool is expected to be used interactively rather than automatically; it tends to use the primary database as the source of its data, which will therefore be available only for the specific time points for which data was logged (which will depend on the package and its settings) and not for any 'in-between' data or recent unlogged data. The XY plot is generally used for analysing past data.

There is considerable flexibility in the way that a graph can be formatted, data from different sensors overlaid, axes scaled and labelled, colours selected for different elements of the graph etc. A set of format options can also be saved as a graph template in some cases. Weatherlink appears to have the most capable general graph utility, with VWS and WV32  less flexible in various ways. 

Raw data

Weather station software often has a utility to view in simple text form (and usually also to edit - for error correction) the data logged to the primary database for that particular package on the PC hard drive. Some packages (eg VWS) use a text-based format in which case a simple text editor - though one able to cope with large files - should be able to view and edit the database. Others use a packed binary format which can result in a smaller database but will require a specific utility for the raw data to be viewed and edited. After months and years of data logging, there can be a large volume of data, so some form of navigation mechanism in the utility is often included. Raw data is commonly stored in compressed form so the raw data view will generally show a more compacted data format and possibly a less well labelled view than some other easier-to-read views. The viewing utility may also include a function to print selected sections of the raw data and also to export selected sections in a format suitable for import into other software such as spreadsheets. 

NB Remember that not all data displayed in graphical trend graphs is necessarily logged into the primary database. In many instances the current view and current trend graphs may update every few seconds, but data is set to be logged to the database only every 5-30 minutes. The in-between data will be lost if the PC is turned off or switched to another application (even in buffered systems) and/or discarded by the system when it is no longer relevant to display. 

Other text reports

A number of other text-based summary formats where daily log records are usually available for specified periods on a day by day basis. These are often referred to as 'reports'. It is natural when analysing weather data to do so for standard calendar periods, ie days, weeks, months and years. This is a minor limitation, although circumstances when a summary of weather conditions is required over an arbitrary number of days are fairly rare.

The various software packages do tend to use different terminology to refer to their summary report formats and this can be confusing, especially as they each differ in the detailed contents of each report. Davis Weatherlink uses the recognised standard layouts of the US NOAA reports as the format for its summary reports. This has a format for monthly and for yearly reports, including values for mean, maximum and minimum temperature, rainfall and so on. Despite being designated a NOAA report, this format is widely useful for reporting monthly and yearly summaries.

VWS can display a full set of min and max values for either the current or any other specific date in one of two similar but distinct windows (the 'Daily Summary Panel' or the 'Archive Panel'). At present there seems to be no general VWS mechanism for creating other summary screens or files. But when used in conjunction with the Davis Weatherlink system, VWS has a mode where it can call the Weatherlink software (pclink4.exe) and use Weatherlink to generate its standard NOAA summary reports. However, it is not exactly clear how this works and the scheduling options would not appear to be appropriate.

VWS also has a facility to store selected data from each day's logged readings (ie presumably a copy of the relevant values in the primary database for that day) as a separate file which is either overwritten on a daily basis or, optionally, given a unique file name for each day. In the latter case a large set of daily files will gradually accumulate. But there seems to be no summary data generated for either file. 

Text reports automatically available for upload

Being able to send summary text reports, for example of yesterday's or monthly data, to a remote server such as a web server seems to be an area where development is lagging in weather station software. Weatherlink can create and save monthly and yearly summary reports to a file, but this seems always expected to be done under manual control. An automated process based on mimicking the manual steps would be feasible but not straightforward.

WV32 does have the option of uploading a specific text file containing an hourly log of data together with min and max values once a day. This is a limited but important option, though there still seems to be no way of uploading monthly summary data automatically. VWS has the ability to upload arbitrary named files and therefore does in principle have a mechanism for moving summary reports to a remote server. If the VWS mode which calls and controls the Weatherlink software is operating correctly, this should provide a mechanism to generate the summary NOAA reports for uploading. However, since Weatherlink always generates the NOAA reports with the same filename, some manual manipulation of files and filenames would be needed at the end of each month for this approach to be used routinely.

Text-based placeholder displays

This viewing mode is primarily intended for web page use.  Placeholder techniques are a mechanism for placing automatically-updating text weather data on to an html web page. Each item on a list of available weather parameters is assigned a unique reference string or placeholder. These placeholders are included on their host web page at whatever positions the page designer requires - often in an html table to allow a neat layout of a number of items of weather data. When the package's FTP upload process is triggered by the internal scheduler, this will also trigger a parsing of the html code in pages marked for upload and the placeholder strings will be replaced by the appropriate current data values and the page then uploaded. 

Email and pager messages

Again described briefly here simply for completeness. VWS, WV32 and Weatherlink all provide options by which weather information can be delivered to email addresses or pagers. In general, other than selecting exactly which parameters are to be sent, the user has little control over the format of the messages. In a related mode, these packages can also send alarm messages by email or pager as and when a preset alarm threshold for a given weather parameter has been passed.