12:25 PM
Figure 6- Strong Upper Level Winds (Black) sperating downdraft and updraft.
Figure 5- Classic Supercell
Figure 4- Conservation Of Angular Momentum Demonstration.
Figure 3- Classic Bath Tub Vortex Caused By Vorticity
Figure 2 Cold air sliding under the warmer air, forcing it to rise.
Figure 1- A Water Molecule, Hydrogen Positive, Oxygen Negative. As result they are connected through Hydrogen Bonds
There are numerous types of thunderstorms such as, single cells, multi cells, squalls, and the most notorious one of them all, the supercell thunderstorm. Instability such as air aloft, warm rising air is needed for thunderstorms to form. During a hot summer afternoon the surface is heated strongly due to the sun's intense radiation. Thus, the surface is heated more than its surroundings above. The molecule's kinetic energy (energy of motion) near the surface will increase as they gain energy. Please note that these molecules are "water" molecules. To put it simply, imagine a pond filled with water, the water temperature will rise as it absorbs more thermal energy. The water molecules are attached by hydrogen bonds and as their temperature increase, the hydrogen bonds moves faster. Consequently, straining the molecules against hydrogen bonds that attaches them. Eventually, they will break free of their bond, and the molecules will be separated, and at this form they are invisible which water vapor is. Now at this stage, the molecules are moving freely in the air in all direction and, and taking more space. So now one liter of volume contains less air molecules than it did previously, and now it is less dense than its surroundings. Now due to the fact that it is less dense, it will rise to higher altitudes, just as a fully inflated balloon will rise as you release it. While the air molecules are still moving freely in all directions, they are crashing into each other, and therefore transferring energy from one another. As this continues, the air molecules will gradually lose their some of their thermal energy, and will attach to one another again by the hydrogen bonds. Keep in mind that all of this is happening while the air is rising; you will have a better comprehension of this once I post a tutorial about adiabatic warming and cooling.
Squall Lines
As the air reaches the cooler regions of the higher levels, it will condense and if air is being raised dynamically enough, enormous towering clouds known as cumulonimbus will form. Now, these typical afternoon thunderstorms are usually short lived, as the downdrafts interferes with updraft, cutting the storms primary source of energy. Squall lines and super cellular thunderstorms on the other hand can last for hours as incessantly regenerate themselves. For example ahead of a cool front, air is being forced upwards, as the cooler air is sliding below the warmer air ahead of it. Thus, the air is very unstable ahead of cool fronts, and a curve line of thunderstorm known as squall lines or bow echoes may form ahead of them. The thunderstorms will continuously regenerate themselves as long as more warm air is being forced upwards. Some squall lines are known to have last as long as 12 hours. Squall lines are known to have produce tornadoes, nevertheless, they are mostly weak ones since new updrafts are constantly being formed and replaced. Isolated super cellular thunderstorms are the ones that typically produce robust tornadoes.
Super cellular Thunderstorms
Supercells are violent rotating thunderstorms associated with an localized area of low pressure known as a mesocyclone. Wind shear, and aloft are the most primary ingredients form these storms to form. Wind shear is the variation (change) of wind velocity (speed and direction) at different altitudes. Wind shear causes vorticity since air has the tendency to rotate at its own axis just like water. Look at Figure 3, the vortex is a result of the unequal speeds of the water. The larger circle indicates where the speed is at its peak, and the smaller circle indicates where the speed is at its lowest. What always happens is that the region where the water is moving at a greater speed will curve to region at lower speeds. Now this may confuse you because, water seems to be moving faster near the center of the vortex. This is mostly due to the fact that it conserves more angular momentum. Imagine a ice skater spinning, you will know that person spins faster as he/she encloses the arms, please look at figure 4. However, in a technical way water is still moving at greater speed at the farther regions of the vortex shown in figure 4. According to physics speed is basically distance over time. The planet earth is rotating faster at the equator than anywhere else in the world. The circumference of the equator is about 24,900 miles, and divide that by 24 hours, you will get about 1038 miles per hour. Meanwhile the circumference of the earth about 40 degrees north is about 18000 miles, and divide that by 24 hours, you will 750 miles per hour.
When a cumulonimbus cloud reaches its mature stage, the updraft when reached to the top of the cloud will be carried away ahead by the strong upper level winds. That is why meteorologists observe the jet stream closely during tornado season. That causes divergence the pressure in the cumulonimbus cloud decreases, allowing more warm air to rise to fuel the thunderstorm even further. Now the unequal speed of the moving air at the different levels of the atmosphere will cause the rising warm air to rotate at its own axis, please see Figure 5. Eventually that will cause a localized area of low pressure to form within the super cell thunderstorm, and when it becomes visible its known as a mesocyclone. Now the potency of the updrafts will not be equal everywhere in the super cellular storm. As a result, the area where the inflow is at its weakest, the air will sink, and rain or hail will fall over that area. Now typically, the occurrence of a downdraft will stifle an ordinary thunderstorm. However, because of the high upper level winds of the atmosphere, the downdraft will not interfere with the updraft, please see figure 6. On my tutorial, I will talk about tornadoes.
Squall Lines
As the air reaches the cooler regions of the higher levels, it will condense and if air is being raised dynamically enough, enormous towering clouds known as cumulonimbus will form. Now, these typical afternoon thunderstorms are usually short lived, as the downdrafts interferes with updraft, cutting the storms primary source of energy. Squall lines and super cellular thunderstorms on the other hand can last for hours as incessantly regenerate themselves. For example ahead of a cool front, air is being forced upwards, as the cooler air is sliding below the warmer air ahead of it. Thus, the air is very unstable ahead of cool fronts, and a curve line of thunderstorm known as squall lines or bow echoes may form ahead of them. The thunderstorms will continuously regenerate themselves as long as more warm air is being forced upwards. Some squall lines are known to have last as long as 12 hours. Squall lines are known to have produce tornadoes, nevertheless, they are mostly weak ones since new updrafts are constantly being formed and replaced. Isolated super cellular thunderstorms are the ones that typically produce robust tornadoes.
Super cellular Thunderstorms
Supercells are violent rotating thunderstorms associated with an localized area of low pressure known as a mesocyclone. Wind shear, and aloft are the most primary ingredients form these storms to form. Wind shear is the variation (change) of wind velocity (speed and direction) at different altitudes. Wind shear causes vorticity since air has the tendency to rotate at its own axis just like water. Look at Figure 3, the vortex is a result of the unequal speeds of the water. The larger circle indicates where the speed is at its peak, and the smaller circle indicates where the speed is at its lowest. What always happens is that the region where the water is moving at a greater speed will curve to region at lower speeds. Now this may confuse you because, water seems to be moving faster near the center of the vortex. This is mostly due to the fact that it conserves more angular momentum. Imagine a ice skater spinning, you will know that person spins faster as he/she encloses the arms, please look at figure 4. However, in a technical way water is still moving at greater speed at the farther regions of the vortex shown in figure 4. According to physics speed is basically distance over time. The planet earth is rotating faster at the equator than anywhere else in the world. The circumference of the equator is about 24,900 miles, and divide that by 24 hours, you will get about 1038 miles per hour. Meanwhile the circumference of the earth about 40 degrees north is about 18000 miles, and divide that by 24 hours, you will 750 miles per hour.
When a cumulonimbus cloud reaches its mature stage, the updraft when reached to the top of the cloud will be carried away ahead by the strong upper level winds. That is why meteorologists observe the jet stream closely during tornado season. That causes divergence the pressure in the cumulonimbus cloud decreases, allowing more warm air to rise to fuel the thunderstorm even further. Now the unequal speed of the moving air at the different levels of the atmosphere will cause the rising warm air to rotate at its own axis, please see Figure 5. Eventually that will cause a localized area of low pressure to form within the super cell thunderstorm, and when it becomes visible its known as a mesocyclone. Now the potency of the updrafts will not be equal everywhere in the super cellular storm. As a result, the area where the inflow is at its weakest, the air will sink, and rain or hail will fall over that area. Now typically, the occurrence of a downdraft will stifle an ordinary thunderstorm. However, because of the high upper level winds of the atmosphere, the downdraft will not interfere with the updraft, please see figure 6. On my tutorial, I will talk about tornadoes.