The Science Behind Thunderstorms and Tornadoes
Understanding thunder and lightning
It might seem hard to believe but where there is thunder there is always lightning, and vice versa. Since lightning can be seen as far away as 100 miles in clear conditions, you might not hear thunder, which is typically only heard less than 15 miles away in quiet country settings, and in metropolitan areas that distance shrinks to about five miles.
You might know that lightning is caused from electricity, and might have even heard that thunder is the sound of lightning, but you might not know what really causes it.
Ice in thunderstorm (cumulonimbus) clouds forms when raindrops freeze. As the pieces of ice bump and rub together, they create an electrical charge. That electrical charge quickly fills up the cloud, with protons on top, and electrons at the bottom. Opposites attract, so when the positive charge – protons – build up under the cloud on the ground, it creates lightning.
Thunder is essentially the “sound” of lightning. As lightning bolts travel from the clouds to the ground, a channel, or tear is made in the air. When the light from lightning disappears, the hole closes, and the resulting sound is thunder.
This time of year, thunderstorms and tornadoes wreak havoc in many parts of the country. In fact, for many living in the path of these destructive acts of Mother Nature the mention of a thunderstorm or potential severe weather can make a person’s pulse race and palms sweat.
- The Enhanced Fujita Scale: A History and Explanation
Learn how to rate how strong or weak a tornado is based on the damage it causes using the Enhanced Fujita (EF) Scale and learn about its developer, Dr. Ted Fujita.
It takes the right conditions
Everyone has had those occasions where the weather looks gorgeous and everything is going along until late afternoon when what is commonly called an “isolated” or “pop up” thunderstorm occurs. Torrential downpours, straight line winds, and in some cases hail can hit faster than the weather service can predict these events and they can be severe.
It might seem as if these storms just came out of nowhere, but often, they have been brewing all day long.
Thunderstorms take certain ingredients to happen, such as moisture in the air, fast rising warm air, and something to make it go up. This is called the lift and it can be anything from mountains, to sea breezes to cold or warm fronts.
Most of the time, storms can start building early in the morning and not have the energy to get going until late in the afternoon or evening.
Torrential downpours don’t constitute a thunderstorm, but lightning and thunder do. Sometimes you won’t even hear thunder or see much lightning, but even a little bit can be dangerous.
What makes a storm severe
Any old thunderstorm might not be much to worry about; on a warm night a little bit of thunder and lightning can cool things down, green things up and create a beautiful morning. However, it’s when storms turn severe that things can get a bit hairy.
Thunderstorms tend to turn severe when there is a rapid updraft; or upward moving warm, humid air. When an updraft is moving at about 40 mph or faster, hail begins to form. Large updrafts encourage large downdrafts, and since most severe storms share updrafts and downdrafts, this is where the high winds come into play.
Straight line winds in severe storms have been recorded to be as high as 100 mph, and powerful downdrafts are often mistaken for tornadoes because of their destructive paths. In fact, they have been known to cause downed trees and destroy buildings. When these down drafts have a path of two and a half miles or less, they are called microbursts.
What Would You Pack?
What would you most want to have in your emergency storm kit?
Dryline: When a boundary of moisture forms between moist warm air, and dry warm air. A dryline is just one of the kinds of weather fronts that can cause severe weather. Drylines are a fairly common cause of severe weather in the Central Plains states, and increase the potential for tornadoes to develop. When a dryline passes an area, there is usually a noticeable drop in humidity levels. This occurs in the US when dry air from the East meets moist Gulf air.
Wind Shear: This is what a change in direction and speed of wind over short time or distances is called. Vertical wind shear is the most frequently shear that meteorologists describe. A wind shear that has a horizontal velocity of a minimum of 15m/sec over a distance of about two to seven miles. With vertical shear, severe is when wind speeds change at rates higher than 500 ft/min.
- Weather Wiz Kids weather information for kids
Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the
Severe weather safety tips
The most seasoned severe thunderstorm and tornado watcher knows how quickly a tornado or severe storm can seem to pop up. Despite the fact that all the ingredients are there for quite some time before these storms occur, the average person won’t realize there is going to be a severe weather outbreak until it is literally on top of them.
You can be prepared for severe weather well ahead of time, so severe weather doesn’t take you by surprise by following a few simple steps:
- Check the weather daily. There are many really excellent weather apps for smart phones that will help you track the daily potential for storms, so keeping tabs on what’s happening in the skies is easier than ever before. Find your favorite and make checking the weather, and the hourly forecast part of your morning routine.
- Have a safe place to go. In many parts of the country, the safe place is a cellar or a basement, but in other common tornado rich parts of the country, there are no basements. Choose a windowless place, such as a hallway, closet or even a bathroom at the interior of your home as your safe place. Make sure all doors to rooms with windows are closed to prevent debris from flying into hallways.
- Pack a storm bag. What you choose to have in your storm bag is your business, but you should have a flashlight, cell phone charger, water and some snacks. A blanket is also a good idea to have in your bag. Extra batteries help, too. Some people choose to keep essential information in their storm bag, as well as a change of clothes.
- Put your shoes on. This might sound crazy, but if a tornado hits and you don’t have shoes on, you’ll be risking cutting your feet on debris left behind from the storm. Make sure that everyone in your home has their shoes on in the event of a tornado warning.
- Get a weather radio. Weather radios wake you up with a shrill alarm in the event of a tornado warning. Many smart phone weather apps have the same feature, so make sure that you have something that will alert you if you have a severe thunderstorm or tornado warning for your area.
When severe storms become tornadoes
Storm watchers around the country, and in the Central Plains states, as well as states like Tennessee, Georgia, Alabama and Mississippi are all too familiar with the terms, “supercell storms,” and “squall lines.” In weather speak in these parts of the country, this is a sure sign that bad weather is about to come and that attention should be paid to the skies.
In the case of tornadoes, two different air masses meet, and create an unstable air mass. Often, it is the relatively dry continental air mass from the west, and the moister warm air of the Central Plains and eastern part of the country. When the two air masses meet, they create what is called a “dryline.”
Supercell thunderstorms are often the cause of tornadoes, because of the potential for strong rotating updrafts. Experts feel that vertical wind shear differences are part of the cause of rotation in thunderstorm cells.
Large scale rotation inside thunderstorms is referred to as a mesocyclone, and this is where a tornado will stem from.
USATODAY.com Latest News
Thunderstorms are dangerous
Late spring and summer are times when outdoor activities are common, and it is also the time for thunderstorms to pop up seemingly out of nowhere. It is important to remember that no thunderstorm is safe, because of the risk of lightning strikes. Remember, if you hear thunder, there is lightning – even when it’s buried in the clouds – so it’s important to stay safe during storms.
When you hear thunder, you should take shelter in a building or vehicle. Do not stand under metal structures, and do not stay outdoors while it is thundering, as you are putting yourself at risk. Instead, keep in mind that the average thunderstorm lasts only about 30 minutes before moving on, so take shelter and wait a storm out.
Watch a Forming Tornado
- How to predict weather from nature
As a backcountry traveler, learn how to predict weather and to take appropriate action for not getting into trouble and risk your safety.
How to tell if severe weather might be headed your way
You don’t need to be in contact with civilization to determine if severe weather might be headed your way. In fact, “old timers” in many farming or rural communities can tell you that there are ways to tell if you will be experiencing severe weather soon.
You can see clues in everything from animals to the skies to leaves on trees, and here are a few that might help you to spot severe weather before it comes:
- The old saying, “red sky at night – sailor’s delight; red sky in the morning- sailor take warning,” is actually true. So, if you’re spending time outdoors, pay attention to this one.
- Pay attention to the way animals behave. Birds that eat worms and bugs will often flock in the morning if a storm is coming in the afternoon. Even dogs have telltale signs of nervousness as severe weather gets closer. If a thunderstorm is going to be severe, or if a tornado is coming, animals take shelter, so if the birds stop singing and hide, you should plan on hiding, as well.
- When rain or thunderstorms are coming, the leaves of plants often turn up to form a cup. In nature, this is so that they can catch more water, but for you it’s a pretty good indicator that you might be getting some rain or weather pretty soon.
- A sudden drop in temperature, or high winds. Often, as a storm approaches, you will notice that the temperature drops significantly and the wind seems to pick up. This is due to the downdraft of the storm, which often precedes it. It’s also a good sign that you need to take shelter soon.
- You smell rain, or ozone. Some thunderstorms will create the definite smell of ozone in the air before any rain has fallen. This is often a sign that thunderstorm and lightning are close and you should take shelter.