3. What are tornadoes? How do they originate? Aren’t they similar to cyclones? Examine.
बवंडर क्या हैं? उनकी उत्पत्ति कैसे होती है? क्या वे चक्रवात के समान नहीं हैं? जांच करें।
A tornado is a violently rotating column of air that extends from a thunderstorm to the ground. It is a vortex of rapidly moving air. A tornado forms when changes in wind speed and direction create a horizontal spinning effect within a storm cell. This effect is then tipped vertical by rising air moving up through the thunderclouds.
Winds within the tornado funnel may exceed 500kmph. High velocity winds cause most of the damage associated with these weather events. Tornadoes also cause damage through air pressure reductions. The air pressure at the tornado centre is approximately 800 millibars (average sea-level pressure is 1013 millibars) and many human made structures collapse outward when subject to pressure drops of this magnitude.
Distribution of Tornadoes in the world:
- Tornado formation typically needs the four ingredients: shear, lift, instability, and moisture.
- Wind shear is the most important factor that plays into the creation of tornadoes. When there is wind shear, sometimes these winds begin to roll into a horizontal column of air.
- Once you get a strong updraft of air being transported from the ground to the atmosphere, that column of air becomes vertical. That is when a storm usually develops in this scenario.
- As the storm develops, it turns into a supercell thunderstorm much of the time. These supercell thunderstorms are separate, discrete cells that are not part of a line of storms. Also, supercells are storms that rotate and spin. With both the vertical, rotating column of air and the supercell thunderstorm together, that may bring down a tornado from the storm cloud
- Tornadoes are most common in spring and least common in winter. Spring and fall experience peaks of activity as those are the seasons when stronger winds, wind shear, and atmospheric instability are present. Tornado occurrence is highly dependent on the time of day, because of solar heating.
- United States has the most violent tornadoes. At any moment there are approximately 1,800 thunderstorms in progress throughout the world.
Differences between Tornado and cyclone
|Definition||A tornado is a rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud. Winds 40-300+ mph.||A cyclone is an atmospheric system of rapidly circulating air massed about a low-pressure centre, usually accompanied by stormy often destructive weather. Storms that begin in the Southern Pacific are called cyclones|
|Rotation||Clockwise in the southern hemisphere and counter clockwise in the northern hemisphere||Clockwise in the southern hemisphere and counter clockwise in the northern hemisphere.|
|Forms of precipitation||rain||Rain, sleet, and hail|
|Frequency||The United States records about 1200 tornadoes per year, whereas the Netherlands records the highest number of tornadoes per area compared to other countries. Tornadoes occur commonly in spring and the fall season and are less common in winters||10-14 per year|
|Location||Tornados have been spotted in all continents except Antarctica||Southern Pacific Ocean, Indian Ocean. Cyclones in the northwest Pacific that reach (exceed) 74 mph are “typhoons”.|
|Occurrence||Places where cold and warm fronts converge. Can be just almost anywhere.||warm areas|
Tornadoes as well as cyclones both occur in India. However, unlike cyclones the frequency of tornado outbreak is very low. Cyclones originate in the Bay of Bengal region as well as in the Arabian Sea region where as Tornadoes of weak strength occur in north-western and north-eastern region of the country causing significant damage to man and material.