InerziaLightning Help (ver 1.0)

InerziaLightning is a very simple widget, whose goal is to calculate the distance dividing us from a thunderstorm, by measuring the time it takes between a lightning bolt and the thunder. Obviously, its precision strongly depends on our readyness to click on the button at the very moment of the lightning and thunder.

Info

By considering instantaneus the vision of the lightning bolt (thanks to its extremely high speed), the distance is obtained with the following formula:
D = Vs * t
where Vs is the sound speed and t the time interval the thunder takes to reach us. To be more precise, the widget consider the dependence of this speed from the air temperature:
Vs = 331,4 + 0,62 * T
where the temperature T is measured in °C (more info at Wikipedia).

Help

The front side contains only 2 elements:
lightningFront

1. Start/Stop Button
A click on this button makes the count to start, another click stops it; the button label identifies the waited event: "Lightning" (count start) or ""Thunder" (count end).
2. Measured Distance
This display shows the distance count (updated every 0,1 s) and after the stop it shows the measured distance; the background color is an evaluation of the dangerousness (red: very near, yellow: moderately near, green: far or very far).
3. Distance Unit
It is selected on the back of the widget, it can be from meters to miles.
As usual, by hovering the widget, the info button appears, that leads to the back of the widget.

The back side let you set the preferences:
Lightning back

1. Temperature Unit
You can choose among Celsius degrees (°C), Farenheit degrees (°F) and Kelvin scale (K); when the unit is changed, the value in the Temperature field is converted to the new unit.
2. Temperature
It is used to calculate the speed of sound; an approximation of two degrees is sufficient.
3. Distance Unit
You can choose SI units (meters, chilometers) or US units (yards, miles, nautical miles and foot); also in this case, when a new unit is selected, the value contained in the front field is converted.
4. Help
It opens in the browser this page, to keep the widget light.
5. Return
The setting part is closed and the Front is shown.
6. Version
It is the widget version.