light - NLDN lightning display program


light [parameters...] filename


Command Line Resource Default Description
-h help No Lists basic help information.
-df=filename default .wxpdef Sets the name of the resource file.
-na=name name light Specifies the name used in resource file parsing.
-ba batch No Run program in batch mode
-me=level message out2 Specifies level of messages to be displayed
  • file information - mess
-fp=filepath file_path current directory Specifies location of database files.  
-dp=datapath data_path current directory Specifies the location (path) of the input raw data files. This may be modified in the name convention file.
-cp=conpath con_path current directory Specifies the location (path) of the input surface converted data files. This may be modified in the name convention file.
-rp=rawpath raw_path current directory Specifies the location of the output raw files generated by the program. These files will not be generated unless the out_file resource is specified and the output is plotted data.
-gp=gridpath grid_path current directory Specifies the location of the output grid files generated by the program. These files are not generated unless the out_file resource is specified and the output is a gridded field.
-ip=imagepath image_path current directory Specifies the default location of the output GIF images generated by the program.
-nc=name_conv name_conv name_conv The name convention file specifies how files are named in WXP. This sets which name convention file to use.
-inp=input input albany Specifies the input file type. The default is albany. Possible values are:
  • albany -- Albany format
  • unisys -- Unisys format
-if=in_file in_file nldn Specifies the input file name tag. The default is nldn, but it can be modified to any value in the filename convention file. A full name convention can be specified as well.
-of=out_file[,out...] out_file None Specifies what type of output file. There is no output file created by the program but GIF files can be created.
-mf=mapfile[,...] map_file or
cont.dat, country.dat for domains outside North America
Specifies the name of the map database file. Multiple maps can be specified along with attributes to describe how to draw the map.
-cu=[hour|la] current None This specifies to use current data files. The current filename is based on the name convention. An optional hour can be specified for older data. If la is specified, the program will search back to find the most recent available file.
-ho=hour hour None This resource specifies the exact hour that a data file is valid for. This locks in the start hour for a multi-file sequence.
-nh=num_hour num_hour 0 (no loop) This specifies the number of hours that will be used in the plot. If this is not specified, a single hourly plot will appear. If this is specified, a loop of plots over this time will be generated.
-pd=domain plot_domain User prompt
Batch: first domain in wxp.reg file.
This specifies the plotting domain. The projection, aspect ratio and the domain size are specified.
-re=region region Same as plot domain This resource is synonymous with the plot_domain.
-va=variable variable intens This specifies the variable to use to color the strike points:
  • intens - intensity of strike
  • time - the minute of the strike
  • flash - the number of flashes
-sc=scale_factor plot_scale 1.0 Specifies a scaling factor for all plotted text, symbols, vectors, etc.
-fm=format plot_format None Specifies the output format of the plots.  This is generally used to specify how many decimal places get displayed on the plot and in the output raw files.
-pp=param[,param...] plot_param None Specifies additional plotting parameters. See the plot_param resource for more details.
-dr=drawable[,...] draw all Specifies which part of the plot is to be drawn.
-la=label[,...] label Program defaults Specifies the labels to be plotted around the plot. By default, labels are generated by the program and plotted above and below the plot. This resource overrides these labels.
-in=interval con_interval None for plots, User prompt for grids. Batch: 0 Specifies the contour interval to use in contouring grids. This can also be used to color code plotted data and vectors.
-cb=base con_base Lowest contour value, maximum wind speed Specifies the base value for color fill contours, and wind speed per grid distance. For more details, see the con_base resource.
-fl=font_list font_list modern.fnt Specifies a list of fonts to use in the plots.
-ct=color_table color_table wxp.clr Specifies the color table to use in the plot. This maps color names to actual RGB color values.
-cot=color[:attr] color_text white
for inverse plots.
Specifies the text color for labels above and below the plot.
-cod=color[:attr] color_data green Specifies the color for plotted data.
-com=color[:attr] color_map red Specifies the color for background maps.
-coln=color[:attr] color_line magenta:st=dsh Specifies the color for lat/lon lines.
-cowd=color[:attr] color_wind white
for inverse plots.
Specifies the color for wind barbs.
-cocd=color[:attr] color_cloud white
for inverse plots.
Specifies the color for cloud cover symbols.
-cowx=color[:attr] color_wx yellow
brown for inverse plots
Specifies the color for weather symbols
-cofr=color[:attr],... color_front A predefined color set Specifies the colors for fronts and pressure systems.
-cocm=color[:attr] color_cmap black Specifies the color for color fill contour maps.
-coco=color[:attr] color_cont white
for inverse plots.
Specifies the color for line contours.
-cof=[val:]color[:attr],... color_fill A predefined color set based on the wxp.clr color table Specifies the color fill contour color set. See the color_fill resource for more details.
-cola=color[:attr] color_label white
for inverse plots.
Specifies the line contour label color.
-cocl=color[:attr] color_clabel black Specifies the color fill contour label color.
-de=device[,...] device User prompt
Batch: display
Specifies the output device.
-ti=title title Program name Specifies the window title.
-ic icon Off Specifies whether to open window in iconified mode.
-bg=color background black
white for inverse plots
Specifies the background color of the window.
-ge=geometry geometry 640x480 Specifies the window and paper geometry.
filename[#seq] filename None
User Pompt
Batch: current=la
The name of the surface converted data file to be plotted. An optional sequence number can be added to designate the time for non-WXP files.


This program plots lightning strike data on a background map. The input to the program is a NLDN lightning file. Then, based on a plot domain and a variable selected by the user, a plot is generated. Overlay plots, contour plots and loops can also be generated if the appropriate options are set.

The programs starts off by prompting the user for input converted file name.  The input file can either be in Albany or Unisys format.  The default is Albany but Unisys can be specified with in_file set to unisys. The user may specify the input file either via the command line of through the current resource. The input naming convention is specified by the nldn tag no matter whether in_file is set to unisys or albany.  The tag can be changed with the in_file resource. To generate a loop, the num_hour resource can be specified. This will tell the program to loop through this number of hours.

Next, the program prompts the user for the plot domain. This is done through a region menu which has predefined regions available. If needed a full plot domain can be specified to get a precise domain. The domain can be interactively changed using the mouse once the plot has been generated.

After the region has been set, the lightning data will be plotted. The program will now open the graphics window and start processing the data. The user will be prompted for the output device. Initially, a map is plotted. Then, the lightning data file is opened and read in. A point is plotted for each strike. The strike data will be colored based on a variable type.

Variable Description Color Fill
intens intensity of strike (default) -500:blue, -300:lblue, -200:cyan, -175:lcyan, -150:green, -125:lgreen, -100:brown, -50:yellow, 0:red, 50:lred, 100:magenta, 150:lmagenta, 200:lgray, 300:white
time the minute of the strike 0:blue, 5:lblue, 10:cyan, 15:lcyan, 20:green, 25:lgreen, 30:brown, 35:yellow, 40:red, 45:lred, 50:magenta, 55:lmagenta
flash the number of flashes 1:blue, 2:cyan, 3:green, 4:brown, 5:red, 6:magenta

NOTE: The Unisys format does not contain intensity or number of flash information.


   light -cu=la -re=mw -de=d

This plots a lightning strike map colored based in intensity.



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Last updated by Dan Vietor on June 11, 1998