Understanding the composition of Earth's ionosphere has recently been made simpler through the release of an interactive program that portrays the composition and layering of the ionosphere in 4-D. In this context, the fourth dimension is time.

Earth's ionosphere is one of the most important elements influencing long range HF radio wave propagation (antennas, ground effect, and numerous other factors have a role also). Most of the space weather reports we easily receive include a number of facts that can help the informed amateur radio operator determine the present state of the ionosphere. Some reports include data that can indicate trends It is the ionosphere, in conjunction with the surface of Earth, the causes sky waves to bounce hundreds or even thousands of miles away from the a transmission site. With these factors in mind, we wish to tell you about a website that can help amateur radio operators (and others) understand the workings of the ionosphere.

NASA and Google have teamed up and developed a project that allows one to swim through the ionosphere. The end result of the project is a computer program with the acronym of CAPS (Communication Alert and Prediction System). Through the use of the CAPS program one is able to visualize and better understand how the various components of the ionosphere form the charged particle and ionized gaseous layers of the ionosphere. It is the presence of charged components (and their densities) that gives uniqueness to the changing layers of the ionosphere. It is the unique qualities of the ionospheric layers that principally influence the paths that radio waves will take as they move from the somewhat homogeneous atmosphere near Earth's surface toward the vacuum of deep space. The computer program that these agencies developed allows one to figuratively swim through the ionosphere. The website hosts a 4-D representation of Earth's ionosphere. The fourth dimension is the dimension of time.

The CAPS program operates in real-time. The program's data is updated by NASA every 10 minutes. CAPS is a interactive program that is built on the "Google Earth" foundation. "Google Earth" is a program developed by the Google company that allows one to fly over a 3-D representation of Earth's surface. The CAPS project was funded through the "Living with a Star Program".

The representation of the ionosphere, is a result of a chain of events, beginning with space weather data (derived from solar activity measurements ) transmitted to Earth from a satellite system. The raw data is then converted into electron densities, which are fed to CAPS. A color scale is used to represent electron density. Red is a high density of electrons and blue represents is a low electron density . As mentioned earlier, the CAPS data is updated and refreshed for viewing every 10 minutes.

The system requirements necessary to run CAPS are rather stiff. Basically the requirements are the same as those necessary to run "Google Earth". If a computer can run "Google Earth" then it can run CAPS. Help for those having difficulty getting "Google Earth" and "CAPS" to run may be available on one of the Google websites.  Specifically the requirements are:

Minimum Configuration
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- Microsoft Windows 2000 or XP
- Pentium 3, 500Mhz
- 128M RAM
- 400MB disk space
- Network speed: 128Kbits/sec
- 3D-capable video card with 16Mbytes of VRAM
- 1024x768, "16-bit High Color" screen

Recommended Configuration
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- Microsoft Windows XP
- Pentium 4 2.4GHz+ or AMD 2400xp+
- 512M RAM
- 2 GB of free disk space
- Network speed: 768 Kbits/sec or better (DSL/Cable)
- 3D-capable video card with 32 MB of VRAM or greater
- 1280x1024, "32-bit True Color" screen

The following graphics cards will not run Google Earth:
- ATI Rage Mobility
- ATI XPERT
- ATI 3D Rage

A webpage that gives a great deal of supplemental information for the Communication Alert and Prediction System (CAPS) program can be found at a website maintained by the Space Environment Technologies (SET) Corp. at the following URL: http://terra1.spacenvironment.net/~ionops/index.html .  Excellent illustrations of current global communication status can be found here. The information maintained at this website is independent of the CAPS program. This means that even if you are unable to run the CAPS program because of computer limitations, you will still be able to access the data used by the program.

Excellent propagation data for nowcasting, in graphic and tabular formats, is available to all on the SET website- and it is in a format similar to that used by the CAPS program. Data driving the graphics on the Space Environment Technologies website is updated every 15 minutes. Data for the CAPS program itself is updated every 10 minutes.

A possible limitation to the use of this website exist in the fact that the terminology used is technical.  This limitation is outweighed by the excellent graphics used. A great deal of knowledge concerning current ionospheric conditions can be gained using only the graphic illustrations.

Information on radio availability and related ionospheric conditions specific regions of the world can be accessed by left clicking on illustration marked Regional Conditions.