THUNDERSTORMS AND LIGHTNING
Summertime is a good time for outdoor recreational activities in New
England. It is also the time of the year when thunderstorms are most
likely. Thunderstorms can be beautiful, but they also can be deadly.
While many people think they are aware of the dangers of thunderstorms
and lightning, the vast majority are not.
There are three basic ingredients needed for the formation of a thunderstorm.
They include low-level moisture, an unstable atmosphere, and a trigger
(a source of lift).
- Low-level moisture:
- This moisture is needed for cloud formation, growth, and the development
of precipitation within the cloud.
- Unstable atmosphere:
- An unstable atmosphere allows warm, moist air near the ground to rise
rapidly to higher levels in the atmosphere where temperatures are below
freezing. An unstable atmosphere also allows air at higher levels in
the atmosphere to sink to the ground level rapidly, bringing stronger
winds from the higher levels to the ground.
- A trigger:
- Something to set the atmosphere in motion.
All three ingredients contribute to the formation of a thunderstorm. In fact,
as the magnitudes of these ingredients increase, so do the chances that a
Thunderstorm could become severe.
In the summertime, listen to the latest forecast and learn to recognize the
signs which often precede thunderstorm development. Warm muggy air is a sign
that ample low-level moisture is available for thunderstorm development.
Towering cumulus clouds indicate an atmosphere that is, or is becoming,
unstable. And, the trigger could be continued heating from the sun; an
approaching front or sea breeze front; or a cooling of the upper atmosphere.
All thunderstorms go through various stages of growth and development. As a
thunderstorm cloud continues to grow, snow and ice begin to form in the
higher levels of the cloud where temperatures are below freezing and
electrical charges start to build up within the cloud. Negative electrical
charges near the middle and base of the cloud cause a positive charge to build
up on the ground under and near the thunderstorm. Finally, when the
difference between these charges becomes to great, a giant atmospheric spark
that we call lightning occurs.
Lightning is an underrated killer, usually claiming its victims one at a time.
Lightning also leaves many victims with life-long serious injuries. Lightning
can strike as far as 10 miles from the side of the thunderstorm cloud. In fact,
many lightning victims are struck before the rain arrives or after the rain has
ended and the storm is moving away. Most victims also report that at least a
portion of the sky was blue when they were struck.
While inside a home or building
- Avoid any contact with corded phones.
- Avoid any contact with electrical or electronic equipment or
cords that are plugged into the electrical system.
- Avoid any contact with the plumbing system. Do not wash
your hands, do not wash the dishes, do not take a shower, or
do not do laundry.
- Do not stand next to a concrete wall and do not lie on a concrete floor.
- Stay away from windows, outside doorways, and porches.
Tips while outdoors
- Plan outside activities so that you minimize the risk of being
caught outside in a thunderstorm.
- If you hear thunder, move inside a safe shelter immediately.
Generally, if you can hear the thunder, you're within striking
distance of the storm.
- If the sky looks threatening, move inside immediately. Don't
wait for the first stroke of lightning. It could occur anywhere
under or near the storm.
- Stay inside a safe shelter for at least 30 minutes after the
last rumble of thunder was heard. Many lightning victims are
struck after the worst part of the storm has passed.
- If you are caught outside in a thunderstorm and can't reach a
safe shelter, you can only minimize your risk of being
struck by lightning. If lightning strikes near you, it will
most likely strike the tallest object in your immediate
vicinity. First, don't be the tallest object in the immediate
vicinity and don't be near the tallest object. Second, get as
low as possible to the ground, but minimize your contact with
the ground. Do not lie on the ground.
Remember, when it comes to thunderstorm safety, it's your own actions that will
determine your personal risk of being killed or seriously injured by the
hazards of a thunderstorm.