**Storm** – intense rainfall, rain and hail accompanied by electrical discharges in the atmosphere, i.e. **lightning** and **thunder**.

**Lightning ** - in meteorology, a very strong electrostatic discharge in the atmosphere that occurs naturally, usually accompanying thunderstorms. Lightning is often accompanied by a sonic impact. It can take many shapes and extensions, form straight lines, or branch upwards or downwards. There are lightnings that are visible only as a brightening of the cloud surface, others again in a fraction of a second resemble a shining string of pearls.

**Thunder ** - the sound produced by lightning. Depending on the type of lightning and how far it is from the listener, the thunder can range from a sharp, loud crash to a long, low growl. A sudden increase in air pressure and temperature due to a lightning strike causes it to expand rapidly, which in turn causes a sound of boom.

The distance of the phenomenon from the observer can be calculated by knowing the time distance between seeing the lightning bolt and hearing the thunder.

Since light travels faster in the air than sound, an observer standing far enough from the lightning strike will see lightning sooner than he will hear thunder. Knowing the time elapsed between noticing these two phenomena, it is possible to calculate the approximate distance from the lightning strike.

The speed of light in the air is a relatively short distance so we can ignore it. To determine the distance at which lightning struck, it will be necessary to calculate the speed of sound.

The most important factor affecting the speed of sound is temperature, to a small extent it is influenced by air humidity and pressure, therefore the last two values will be omitted.

The experimental formula for the dependence of the speed of sound in dry air is given approximately by the formula: $$ v=\left[331{,}5+(0{,}6\theta )\right]\ \mathrm {\frac {m}{s}} $$ where:

v – speed of sound,

θ – temperature in degrees Celsius [°C].

This formula approximates the formula resulting from the ideal gas equation: $$ v=331{,}5{\sqrt {1+{\frac {\theta }{273{,}15}}}}\ \mathrm {\frac
{m}{s}} $$