How to use the Stromboli bomb trajectory program
Using the applet should be mostly intuitive. Just a few tips regarding features which may not be so obvious: Click into the map to select the direction in which the bombs should be launched. Note that the terrain in the profile below the map will be adjusted automatically. It is based on real Stromboli topography. The exit point of the bombs is assumed to be roughly in the middle of the crater terrace. You cannot change this point.
Calculating bomb trajectories in real time (check box) gives an excellent feeling for how long it takes a bomb to reach a certain point. You do not have to wait until they impact. You may launch several bombs at once, and vary the parameters. To calculate many trajectories it may be better to unchecked real time. Calculation is then almost instantaneous. Clicking a bomb trajectory in the profile below will open an info panel with further data on the bomb and its trajectory:
The bomb's weight is automatically calculated from the values entered for the bomb's diameter and specific weight. Basalt has a specific weight (density) of about 2800 kg/m3. However, bombs ejected from Stromboli's craters arre usualy vesicular, i.e. they contain many gas bubbles which reduce the specific weight. We therefore set the default value for the specific weight at 2000 kg/m3. Some boms will be even less dense.
Bombs come, naturally, in many different shapes. Melted bombs will also change shape in flight. Streamlined drop shapes, as available via the pull down menu, are probably rare. Often bombs have totally irregular shapes which leads ti increased air resistance. However, spherical shape (probably underestimating air resistance) combined with a specific weight of 2000 kg/m3 (probably a bit low, thus overestimating the effect of air resistance) may be a reasonable approximation.
After downloading from the server he applet will work perfectly well offline. In other words you may wish to disconnect from the Internet, and save dialup costs, during longer experiments ;-)