Science Facts - Lapse Rate Animations

Twice every day, radiosonde and pilot balloon observations are made at over 1500 locations world wide (though only about 700 are really useful, the rest don't have enough data). That data is archived by NOAA in the Integrated Global Radiosonde Archive (IGRA).

I have produced a few Flash based graphs to view temperature vs altitude plots (Lapse Rate plots). Unfortunately, Flash programs are too slow for anything more complicated.

I wrote LapseRateAnimation.exe (a Windows XP program) to look at a full year (or more) of temperature profiles as an animation. provides the program (a stand-alone *.exe file that does not make any registry changes) and several sample data sets. (Version works with Vista and has an improved user interface .. version does not work with Vista. Version changed the Legend lable from "Dew Point" to "Dew Point Diff".)


Most of the Lapse Rate Animation program is self explanatory. The zip file also comes with several datasets - just select one from the combobox.

This example shows

A large number of soundings contain at least one unknown height (value = -9999). These normally occur when the temperature reaches a minimum at the top of the troposphere (near 12,500 meters in this example). In order to display these points, I have used a linear interpolation (which produces a small error) to determine a value from the provided pressure.

The following sample datasets contain all the available data for 2006 at the associated site. It is fairly common for some data to be missing.

Notice that between 5,000 and 10,000 meters, the temperature of the troposphere changes very little between day and night. This is the primary evidence that this part of the atmosphere does not radiate IR energy directly to the surface. The longer term changes are usually produced by wind and/or weather fronts.


Displaying Additional Data

The data in the zip file is representative - coastal, desert, polar. Since I don't want anyone to accuse me of cherry picking the examples, the program allows you to retrieve any dataset available from the Integrated Global Radiosonde Archive (IGRA) and display it yourself. Unfortunately, the procedure is manual.

As of 07-13-11 (and still down 07-31-11), the NOAA site has a problem and the method described in this section no longer works. Please see the next section for a technique which still works. I am leaving the following because it may just be a temporary problem.

Currently not Functional

The basic procedure is to select a sounding site and some number of soundings. (I have tested the software with 3 years of data and it seems to work fine.) Starting from the station selection page, select United States and one of the available stations.

I have tried many times, but so far I have not been able to get data for locations outside the United States. It appears that the data is available, but a bug in their software blocks filtered access. The next section describes how to download the compressed data and process it with Process_Raw_Data.exe so that non-US data can be displayed. The rest of this section applies to US data only.

On the next page, be sure to select Multiple Soundings, the default returns only a single set of measurements. The other setting on this page (the date range) is not particularly important.

On the next page, you need to select the start and end dates - I find it easier to just type them in. For my program to work, be sure that the following options are selected (I may fix this later).

When you click Continue, an html page will be displayed in a new window. This file contains the data and must be saved on your local machine. With IE, I select View Source and then save the file in the same directory as the program.

Warning - be sure to wait for the file to finish downloading before saving a local copy.

In the program, just click the Read File button and select the file you saved. The extension does not matter.

Warning - Because there is limited error checking, if you give it the wrong type of data file the results are not predictable.

Using Process_Raw_Data.exe

LapseRateAnimation.exe works by processing the html files produced by NOAA. Unfortunately, of the 1,500 global sites available via ftp, the NOAA web interface provides the data in an html format for only the US sites. (As of 07-13-11, none of the html files are currently available .. their server produces an Internal Server Error .. which I reported.) In order to view the data from those additional sites, I wrote Process_Raw_Data.exe to make the conversions. Unfortunately, the procedure is still fairly manual. I know that this is a poor way to write software, and someday I might fix it. But at least it works.

The main problem is file size - the raw files are very large. My procedure is to edit the raw file and to save one or two years worth of data in a separate txt file which is then processed.

This is not a good (or user friendly) design ... but it works.

The main ASCII text edit program I use for this is MS WordPad (because it reads unix terminated data files). You must save the selected data as a *.txt file and not an rtf.

Process_Raw_Data.exe reads the selected *.txt file and defaults the output filename to have an *.html extension.

The data is accessed in LapseRateAnimation.exe by using the Read File... button.

Download Process_Raw_Data.exe

Archive Details

The Integrated Global Radiosonde Archive (IGRA) provides the following

Important Data Fields

Since this procedure requires manually editing the raw data, it is necessary to understand the format.

This is a sample of the raw data

Each sounding starts with a header that contains the site ID and a date/time stamp. Understanding the data.

I have identified only those fields you need to make the necessary edits .. a full description is available.

ini File

Version allows the user (that means YOU) to add data files to the combo box. You can also set the initial delay between frames. The provided file contains the details.


It is a little weird that the maximum jet stream speed is typically at the same level as the minimum troposphere temperature. I assume that this is a measurement artifact because the balloon is about 85 feet above the sensor package. Since the wind speed is determined by tracking the balloon from the ground, my interpretation of this anomaly is that the balloon is in the jet stream while the sensor package is still in the troposphere.

Data Access

Since this page was first produced (03-06-09), NOAA has changed their interface. Unfortunately, it is no longer possible to access the sounding data in an html format.

Of note, this site indicates that these airports provide soundings every hour for the last 2 weeks. I have not tried to use this data.

Author: Robert Clemenzi
URL: http:// / Science_Facts / Lapse_Rate / Lapse_Rate_Animations.html