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Storm Surge

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Hurricanes have caused billions of dollars of property damage. Your challenge is to determine which land and storm features impact the damage caused by a hurricane that strikes land in a populated region. You will use a simulation to change the power of a hurricane and ultimately find ways that storm damage can be reduced in a coastal area.

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Storm Surge Brochure

What is a hurricane?

A hurricane is a tropical cyclone that occurs in the North Atlantic Ocean, Northeast Pacific Ocean, or the South Pacific Ocean and has winds of 74 miles per hour or more. A tropical cyclone is a low pressure system over tropical or sub-tropical waters with thunderstorm activity and circulation.

How large are hurricanes?

The average hurricane is about 500 kilometers wide with a calm, clear eye of about 50 kilometers. The highest winds are in the wall of the eye.

What factors are required to form a hurricane?

Several factors are needed to form a hurricane. These include: 1) warm ocean waters above 26 Celsius, 2) a distance away from the equator since the Coriolis effect is at a minimum at the equator and will not cause an air mass to spin, 3) warm core storm created by the condensation of water vapor as it rises in the center of the storm, 4) little vertical wind shear that maintain the warm air temperature above the eye, 5) high relative humidity levels, since dry air increases evaporation and cools the core structure, and 6) a tropical wave of thunderstorms.

What causes damage when a hurricane strikes land?

The winds from the hurricane inflict the most damage when a hurricane makes landfall. Flooding can occur due to a combination of rain and the storm surge. In addition, if there is too much rain in a short time period, the ground can become saturated and does not anchor trees solidly making it easier for trees to be blown over by the wind.

How are hurricanes measured?

Hurricanes are measured on the Saffir-Simpson Scale, which ranks hurricanes intensity based on their wind speed, with a category 1 hurricane being the most mild and a category 5 hurricane being the most severe. The wind speeds for each category are as follows:
Category Wind Speed (mph)
1 74-95
2 96-110
3 111-129
4 130-156
5 157+

What causes ocean tides?

The gravitational forces of the sun and the moon, and the rotation of Earth cause ocean tides. Most places on Earth have two high tides and two low tides per day. The high tides happen about 12 hours apart.

What is a storm surge?

A storm surge is a rise in water level in a coastal region as a result of a storm. The storm surge is how much higher the water level is during the storm than it usually with the normal tides. Storm surge is a result of the storm winds pushing water towards land. The low pressure of the storm has a very small effect on the surge, but for the most part storm surge is the direct result of the winds. The storm surge of a hurricane is the most lethal aspect of the storm.

What affects the height of a storm surge?

The height of a storm surge can vary greatly depending on the conditions of the storm and the geographic features of the coastal area. The size, speed, shape, and pressure of the storm, as well as the angle that it approaches land all have an effect on the size of the surge. The width and depth of the continental shelf also have an effect on the size of the surge. A wide and shallow shelf will produce a much higher storm surge than a narrow and deep shelf.

What is a storm tide?

The total height of the water due to normal tides and the storm surge is called the storm tide. The size and timing of the normal tides, the size of the storm surge and the size of the waves all affect the storm tide. If a large storm surge with large waves hits land during high tide, the storm tide can reach as high as 20 feet or higher.

What is the cause of ocean tides?

Tides originate in the ocean and progress toward the coastlines, where they appear as the regular rise and fall of the sea surface. Thanks to Sir Isaac Newton’s 1687 discovery, we know that tides are very long-period waves that move through the ocean in response to forces exerted by the moon and sun. However, these gravitational forces do not control when high or low tide events occur. Other forces, more regional than the moon or sun, control the tides. Many of them have to do with the geography and shape of the Earth.

The shape of our planet has a lot to do with differences in gravitational pull at various locations. If Earth was a true sphere covered by an ocean of constant depth, then it would be true that a high tide event would occur at the location with the moon overhead. The tidal "bulge" would move around the Earth with the moon, but this is not the case with our planet. The Earth is not a true sphere, but bulges slightly at the Equator. It is also dotted with large land masses (continents). Areas where the Earth’s surface is higher, such as mountains, have a stronger gravitational force than do places where the surface is lower, such as a valley or cavern. At the same time, the depth of the world ocean varies greatly. All of these factors play into the height of the tides.

Around the world, there are three basic tidal patterns: semidiurnal, mixed, and diurnal. When both high tides are about equal to each other, and the low tides are also roughly equal, the pattern is called a semidiurnal tide. If the two highs and lows differ substantially, the pattern is called a mixed tide. Where there's only one high and one low tide a day, it's called a diurnal tide. One location can experience different tide patterns throughout the month.

Here are some definitions to help you in your Grade 3-5 Lesson 1 investigation.

Depth - the distance from the top or surface of something to the bottom of something
Meters - a unit of measure of depth. One meter is about 3 feet.
Shelf Width - the part of the continental plate that extends into the ocean and is below the surface to a relatively shallow depth. The shelf varies in width from a few meters to over 1,500 kilometers wide.
Continental Plate - a large part of Earth’s crust
Storm Surge - a rise in the ocean level due to storms pushing water in towards the coastline
Constant - keeping a variable from changing
Manipulated Variable - the variable that the researcher changes. This is called the “cause.”
Response Variable - the variable that the researcher measures. This is called the “effect.”

Here are some definitions to help you in your Grade 3-5 Lesson 2 investigation.

Storm Surge - a rise in the ocean level due to storms pushing water in towards the coastline
Ocean Tides - are caused by the gravitational attraction on the ocean of the Earth, Moon, and Sun System. Most coastlines on Earth experience two low tides and two high tides each day.
Sound - a body of water that connects in two or more places to another body or bodies of water
Barrier Island - a long, narrow island lying along a coast that protects the coastline from erosion due to storms
River Estuary - a part of a coast with brackish water flowing into it from one or more rivers
Spit - a narrow piece of land tied to the coastline at one end
Constant - keeping a variable from changing
Manipulated Variable - the variable that the researcher changes. This is called the “cause.”
Response Variable - the variable that the researcher measures. This is called the “effect.”
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