like a hot air balloon. when the sun comes out, heats the ground, the ground warms up and the air wants to rise. as the air rises into space, it goes up higher and higher and gets into colder and colder air so the particles congeal, the humidity comes in and goes straight up into the air and you see the towering cumulus clouds, like everything in the northern hemisphere that spins to the right and everything in the southern hemisphere that spin to the left. if you move this stuff long enough on the way up, literally, 60,000 feet in the sky, 12 miles from the surface to the top, you will get this spin. eventually, the whole storm spins and then the back half we call it the mesocyclone, the conservation of ang you lar momentum, like an ice skail skater bringing her arms in. she skates and skates faster. the more the closer her arms are in and at the bottom of the mesocyclone a tornado falls out of this storm. well, it has been a month since tornadoes ravaged alabama. coming up next,
that makes a jet stream that s faster than normal. when you get a jet stream moving faster, you get the potential for more sheer. more difference between what the air is doing down here and what the air is doing up here. a faster jet can make and does make bigger tornadoes i. i mean, how does a tornado form? this is cool stuff. particles on the ground, humidity on the ground starts to rise. like a hot air balloon. when the sun comes out, heats the ground, the ground warms up and the air wants to rise. as the air rises into space, it goes up higher and higher and gets into colder and colder air so the particles congeal, the humidity comes in and goes straight up into the air and you see the towering cumulus clouds, like everything in the northern hemisphere that spins to the right and everything in the southern hemisphere that spin to the left. if you move this stuff long enough on the way up, literally, 60,000 feet in the sky, 12 miles from the surface to the top, you will get this
reporter: battle hardened storm chasers in awe of nature s power. oh, my gosh. this is awful. dude, the trees. the trees are debarked! reporter: residents running for cover anywhere they could. in a crowded convenience store some 20 people hunkering down in a darkened commercial refrigerator. can we go in the cooler? [ screaming ] go! oh, dear heaven. god! reporter: at the same time a security camera in a nearby frozen yogurt shop catches the chaos. workers moving customers to the back and then everything goes flying. the massive tornado mowing down everything in its path. people s lives churned up and spewed out. here s the gas station that we were at. reporter: this is the convenience store now. this would have been where we walked in. reporter: all across the city, thousands and thousands of people in shock, taking the first steps on the long road to recovery. make no mistake, joplin, missouri, will rebuild, but it will never be the same. hello an
what s happening. that s ahead. we will have the latest on this developing story in a few minutes from now. president obama is back at the white house of a spending several hours in joplin, missouri. it was exactly a week ago that an f-5 tornado ripped through the city killing people in minutes. 5:41 central time there was a moment of silence marked by the precise instant that tornado hit. our dan traveled with the president to joplin and dan, a tough job for the president to try to lift spirits of a being amongest the people but seeing this disaster first-hand. this is a president who has had to do this quite a bit lately. other natural disasters as well. the president as you know last week was overseas among other things building relationships with european partners. throughout that time, white house aid said the president was getting updates on the situation here in joplin. today the president got to see the devastation up close. before touching down, air force 1 fle