Tornados can produce winds up to and over 250 mph. In rare circumstances, tornadoes winds have been measured up to 379 mph. According to NOAA, about 1,000 tornadoes are reported across the United States in an average year, resulting in 80 deaths and over 1,500 injuries.
Tornados are a violently rotating column of wind that can pick up cars and propel them like missiles. They can lift off roofs or even move houses right off their foundation. Tornadoes are usually produced from thunderstorm storms and can cause a damage path greater than one mile wide and up to 50 miles long. Tornados occur at different times in different locations. Peak tornado season in the southern states occurs during March through May. Whereas in the northern states, the peak tornado season occurs from July to August. There is little known information about how tornadoes form. We do know, however, that tornadoes are normally associated with severe thunderstorms and that unstable air aids in their strength.
Tornados can occur at anytime, but most of them have been spotted in the afternoon and evening hours, because the air is hottest in the afternoon and therefore has the greatest tendency to rise. They also can travel in any direction, but according to NOAA, most tornados move from southwest to northeast, or west to east. Not all tornadoes follow these rules and some change direction, or even backtrack. The length of time that tornadoes last varies from a few seconds to more than an hour but most last less than 10 minutes. Because of all the variation in tornadoes, tornadoes are very difficult to study, and as a result, we know little about them.
There are two main types of tornados: rope (see Figure 2) and wedge (see Figure 3). Rope tornadoes are very long and narrow, and wedge tornadoes are huge and wide. Rope tornadoes can produce stronger winds than wedge tornadoes, and vise versa. Size does not mean strength!
Figure 2. A classic wedge tornado in Shamrock, Texas, in 1977.copyright
What is a tsunami? Well, it is a really large wave — much larger than the waves you see when you splash in a pool or surf at the beach. The difference between a regular wave and a tsunami is that a regular wave is just a surface disturbance of the water, and a tsunami is a disturbance that reaches all the way to the ocean floor!
What do you think causes a tsunami? Well, tsunamis can be caused by anything that moves the ocean or sea floor, like earthquakes, volcanoes and landslides. Think about an underwater earthquake that is caused by the moving of tectonic plates. Do you think that this could move the sea floor and create a tsunami? Yes, it could! Do you think engineers can prevent tsunamis? Engineers cannot prevent natural events like earthquakes or volcanoes, or the tsunamis that can result from them. So, what can engineers do about tsunamis? One thing engineers can do is build structures that can survive a tsunami.
In December 2004 a huge tsunami hit the beach in Indonesia. Do you know from what material most of the destroyed houses were made? Most were made of wood, and some were actually made of paper. What do you think are the advantages and disadvantages of wooden or paper houses? How might houses made of these materials be a disadvantage when it comes to a tsunami? Well, a house made out of weak material, such as wood or paper, probably will not survive the great forces of a tsunami. So, what can engineers do so that a building or structure is able to survive a tsunami? (Possible ideas: Build it out of stronger material; build it on stilts.) What might be some disadvantages of these types of the new houses? (Possible ideas: More costly and difficult to construct, look different than usual buildings.)
Today, we are going to explore some of the choices that engineers have when designing buildings with tsunamis in mind and make some conclusions as to what shapes and materials make the most tsunami-resistant buildings. Today you are going to make a model building and see if it will survive a tsunami. Your criteria is to build a house that will withstand a simulated tsunami given constraints (using only materials provided- tissue paper, cardstock, notebook paper, toothpicks) of this activity. Are you ready?
We are going to have some fun today and learn more about flooding by creating our own mini-floods. Scientists and engineers do these same types of experiments with small-scale models, as well as computer simulations, to understand how real-life floods behave. Using models to make observations and collect data allows engineers to develop effective designs. Does anyone know what a floodplain is? Well, it is the dry land surrounding a waterway, like a river or stream, into which flooding waters spill. An engineer needs to know the area of a floodplain in order to figure out a flood might affect anything located there and if a design solution needs to be implemented
We are going to build mini-houses (models), too, and see if they get wiped out by the flood. This brings up an interesting point. If the human-made buildings were not there, would the flooding be a problem? Probably not. Natural flooding has been occurring for thousands of years. It only becomes a problem when people create something of value in the floodplain, like houses, that might be destroyed in a flood. As it turns out, floodplains are very attractive locations to build towns and cities — until flooding occurs. Why do you think people build houses in floodplains? Well, a floodplain is usually a nice flat area conveniently located near a river that can be used for transportation, agriculture and recreation, and the land is usually good for growing crops because of the rich soil deposited by past floods.
Today we are going to test a few different situations that cause flooding. What might cause a flood to happen? Well, there are a few considerations. The most important one is how much water is in the area. The more water that is introduced into an area (through rain or melting snow), the more likely flooding is to occur. Another important factor is how much space there is for the water to flow or settle into. If the riverbed is constricted or blocked by something like a dam or levee, then the water must find someplace else to go. Since floodplains are large areas, the water can spread out all over the place. Another issue (that is not addressed by this activity) is how much water the ground can absorb. Have you ever noticed that water soaks into the ground after it rains and makes the ground soggy or muddy? Well, different soils absorb different amounts of water, which can affect the amount of flooding that results. We are not going to look at that today, because we are using modeling clay, which absorbs essentially no water.
(Show students the attached PowerPoint presentation, Floods, Floodplains and Levees, to provide a visual understanding of floods, floodplains and levees. Or, print out some of the images to pass around class during the introductory discussion.)
Some engineers study flooding, using what they learn to protect people and property. They design structures — like dams, dikes and levees — to keep flooding away from populated areas. Today we are going to design a model of a floodplain, just like an engineer would do. We will also record our observations and data in order to better understand how to develop a design solution. Are you ready?
Today is out first day of natural disaster! We are talking about earth! What types of natural disaster relate to the earth/ground?
In this project we will explore rockets and their components to keep astronauts safe. Your challenge is to create a rocket that will protect your astronaut during take off, flight, and landing. Good Luck!
