1. STORMS Formation of the clouds Types of clouds Why does it rain? Clouds of storm Flashes The lightning

2. Formation of the clouds Thermal current: the hot air in contact with the ground is propelled upwards Condensation: with altitude, the air cools and forms a cloud with the condensation of the steam Convection: the cloud develops while rising

3. Types of clouds Cumulus Cumulonimbus

4. Why does it rain? You know now that when water evaporates, the vapor rises, and condenses to form clouds. The clouds move on the earth, and precipitations make fall down water. This water fills the lakes, the rivers and turns back to the oceans where it again will evaporate and starts again this cycle.

5. Clouds of storm The storm is a violent disturbance accompanied by rain, lightning, hail and sometimes by tornadoes.

6. Clouds of storm Development: in a cumulonimbus the water droplets and the snowflakes are raised by draughts Maturity: the crystals remain at the top of the cloud where the temperature reached - 50°C. The large drops fall in strong rain Dissipation: the ascending draughts are replaced by downward violent ones, involving a light rain.

7. Lightning Within the clouds of storm, the ascending draughts separate the electric charges + and -, which generate energy The lightning is the release of this energy which occurs in the sky

8. The thunderbolt Among the many electric discharges, only a small part arrives on the ground (approximately a tenth of the total discharges). The majority of the discharges are intra or inter clouds discharges. Both phenomenon: lightning on the ground + thunder constitutes what is called the thunderbolt