SEVERE SUMMER WEATHER AWARENESS WEEK
May 2nd - May 6th.
http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=fgf&storyid=51423&source=0
Day 2. Thunderstorms, Hail, Wind and Lightning!
http://www.crh.noaa.gov/fgf/?n=severesummer2010_day2
*By far the most popular topic... most meteorologist get excited for Thunderstorms!
One of the best examples of Severe Summer Weather is Thunderstorms. With Thunderstorms comes a varity of different elements that can make it severe... some of those being in the above topic... Hail, Wind and Lightning. Severe Thunderstorms are classified by their winds, if there is hail and its capability to produce a tornado. The qualifications are as follows:
1) Large hail with the diameter of +3/4 inches
AND/OR
2) Wind (at the surface) Gusts at least 58 mi/hour
OR
3) the Capability to produce a tornado
Hail
"Transparent or partially opaque particles of ice, that range in size from that of a pea to that of a golf ball."
Hail is found falling out of Thunderstorms. It forms when a supercooled rain drop (usually frozen) gets stuck in an updraft and is lifted through the updraft, freezes as it goes up. Then it falls out of the updraft into the cloud again. As it is falling it collects water and more frozen drops and gets caught up in the updraft again. This keeps repeating until the stone is big enough to fall out of the cloud.
The largest hail stone to date in the US was 17.8cm in diameter and most likely weighed over 1.75 lbs.
Wind
"Air in motion relative to the earths surface."
Wind is a major factor in every day life, as well as, HUGE thunderstorms. Wind is caused by a difference in Pressure through out the atmosphere. In storms, its often a difference in pressure with in that small storm. Winds in a Thunderstorm can be very dangerous because they can become straight-lined and have the strength of a tornado. Winds anywhere from 58mph to 100mph in a thunderstorm, can help to classify the storm as a Severe Thunderstorm.
Lightning
"IT'S ELECTRIC! BOOGY WOOGY WOOGY"
"A visible electric discharge from a storm"
Lightning can occur 4 ways,
Lightning can heat the air up to 54,000 Degrees or higher. The quick warm up causes the air around the bolt to expand. With the quick expansion there comes a Boom... That is Thunder.
Lightning is caused by the separations of charges between a cloud and the ground, cloud and another cloud or just in the cloud itself. The following are the steps in the formation of lightning.
1) Separation of the charges in the cloud. The negative all collect at the bottom and positive charges start to form on the ground.
2) Stepped leaders - the electrons discharge from the cloud to the ground quickly, in steps. This is invisible to the human eye.
3) The positive charges start to move up off of the ground toward the negative.
4) The two charges meet up and a strong flow of electrons return to the ground creating the bright flash of the "return stroke."
The National Weather Service has some great tips for being safe if you are caught in lightning. They also have some facts and myths about lightning. Check those out through the link at the top of this post.
** All the definitions in this post are straight out of "Meteorology Today" by Donald Ahrens.
"Transparent or partially opaque particles of ice, that range in size from that of a pea to that of a golf ball."
Hail is found falling out of Thunderstorms. It forms when a supercooled rain drop (usually frozen) gets stuck in an updraft and is lifted through the updraft, freezes as it goes up. Then it falls out of the updraft into the cloud again. As it is falling it collects water and more frozen drops and gets caught up in the updraft again. This keeps repeating until the stone is big enough to fall out of the cloud.
 |
| Hail Formation |
Wind
"Air in motion relative to the earths surface."
Wind is a major factor in every day life, as well as, HUGE thunderstorms. Wind is caused by a difference in Pressure through out the atmosphere. In storms, its often a difference in pressure with in that small storm. Winds in a Thunderstorm can be very dangerous because they can become straight-lined and have the strength of a tornado. Winds anywhere from 58mph to 100mph in a thunderstorm, can help to classify the storm as a Severe Thunderstorm.
Lightning
"IT'S ELECTRIC! BOOGY WOOGY WOOGY"
"A visible electric discharge from a storm"
 |
| 1882. |
1) cloud to cloud
2) cloud to ground
3) In-cloud
4) cloud to air.
Lightning can heat the air up to 54,000 Degrees or higher. The quick warm up causes the air around the bolt to expand. With the quick expansion there comes a Boom... That is Thunder.
Lightning is caused by the separations of charges between a cloud and the ground, cloud and another cloud or just in the cloud itself. The following are the steps in the formation of lightning.
1) Separation of the charges in the cloud. The negative all collect at the bottom and positive charges start to form on the ground.
2) Stepped leaders - the electrons discharge from the cloud to the ground quickly, in steps. This is invisible to the human eye.
3) The positive charges start to move up off of the ground toward the negative.
4) The two charges meet up and a strong flow of electrons return to the ground creating the bright flash of the "return stroke."
The National Weather Service has some great tips for being safe if you are caught in lightning. They also have some facts and myths about lightning. Check those out through the link at the top of this post.
** All the definitions in this post are straight out of "Meteorology Today" by Donald Ahrens.
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