Inside a thunder cloud very warm air rises rapidly, cools at the top of the storm cloud, it then starts to descend , then rises again to form convective cells. The extremely turbulent motion causes the top of the cloud to acquire a positive electrical charge and the base of the cloud, a negative charge. It is said to be caused by the collision between small ice particles as they move up and down inside the cloud building up a static electrical charge. Very small positive charged ice crystals accumulate at high level, and falling hailstones acquire a negative charge. This static electricity builds to very high levels within the storm cell until it sparks, and the spark is lightning.

Next Week: Lightning Part 2.

Glossary: Tornado: A violently rotating column of air, usually less than 100 m (330 ft) diameter, surrounding a core of extremely low air pressure. Wind speeds may exceed 320 km/h (200 mph).

Weather for coming week Monday 29th June-Friday 3rd July.

High pressure to the east and low to the west this coming week bringing a south/south-easterly airflow and heatwave conditions. Some of the highest temperatures since the summer of 2006.

Some hot humid sunshine and dry interludes, but the heat and humidity of each day may trigger some slow moving severe high level thunderstorms in places with squally winds, hail and flash flooding as huge amounts of rain falls from these storm heads.

However, due to the stormy nature of the weather, many parts will miss them and stay dry and placid.

Winds sse force 1 (2-5 mph) but strong and squally beneath storm activity.

Some rain or showers passing from west to east on Friday bringing in its wake cooler fresher weather.

Maximum temperature 28-32c 82-90f but 21-22c 70-72f on Friday.

Minimum temperature 16-18c 61-64f but 12-13c 54-55f on Friday.

Last Week's Observations (Monday-Sunday)

Highest day temperature........26.1c on Sunday 28th June.

Lowest night temperature......16.6c on Sunday 28th June.

Wettest day.........................8.3 mm on Friday 26th June.