Summer is the time for lightning. Extreme weather events occur more frequently during the spring and summer months in temperate areas. Beautiful sunny days can rapidly turn stormy with people sent running for cover by torrential rain, hail, gusts of wind and lightning.
It is not, of course, the action of a god disgruntled at not being asked to your barbecue and determined to ruin the fun. There are more thunderstorms during the summer in mid latitude areas because the conditions that produce them are most prevalent.
Thunderclouds, or cumulonimbus clouds, gather as warm, damp air rises. The rising air is normally heated by the ground being warmer than the air above it.
The air consists of gases that expand, becoming less dense, at higher temperatures. This makes the air lighter and so it rises through heavier, colder air. If conditions were humid it takes the water vapour with it and so clouds are formed.
Higher in the atmosphere it is much colder, causing the water vapour to condense. You can see this effect in action when you take a hot shower. The water vapour meets the cold mirror surface and condenses, annoyingly fogging it up. In the clouds this condensation forms water droplets that fall as rain. If conditions are especially cold these water droplets will freeze and fall as hail.
The thunder and lightning that define a thunderstorm are the sound and light of electrical activity. The particles of the thundercloud separate into positive and negatively charged areas and the lightning most commonly shoots from the negatively charged bottom of the cloud to the positively charged top. It can also shoot from cloud to cloud. The most dramatic and dangerous form of lightning is from a negatively charged cloud to the positively charged ground and this can kill.
The intense guests of wind that blow down trees are caused by changes in air pressure. Wind is simply the movement of air from an area of high pressure to an area of low pressure. The conditions that produce the thunderstorm are also changing the pressure of the air. For example the rising warm air is creating a region of low pressure.
High humidity and plenty of solar radiation make thunderstorms possible. If you live in a place that has these conditions most in the summer then be prepared for thunderstorms. In the most extreme conditions thunderstorms can become hurricanes and wreck havoc.
Read next: How does a hurricane form?
There are so many variables that forecasting the weather is still not one hundred percent accurate. However meteorology has come on in leaps and bounds in recent years and by listening to the radio or checking online you will be informed of coming storms and can plan accordingly. When they tell you there is a high chance of thunderstorms this is probably not the best time to be climbing mountains.
