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Radio Viseu Cidade Viriato

sábado, 13 de setembro de 2008

Dental Calculator

Are your teeth older than you?

Did you know that your lifestyle as well as your dental regime could be adding years to your overall appearance, making you look much older than you actually are? Take the quick quiz below to find out if your teeth are ageing you.


segunda-feira, 8 de setembro de 2008

Saffir-Simpson Hurricane Intensity Scale

Intensity Scale is used to categorize hurricane strength and potential damage. Public broadcasts generally include a hurricane’s category. This table shows the parameters (wind speed and storm surge), criteria, and expected damage of each category of hurricane. Note: Damage descriptions are provided in NOAA's "Hurricane and Disaster Brochure". Click a damage level below for a description.

Category Wind Speed Storm Surge Damage

Km/hr mi/hr m ft

1 119-154 74-95 1-2 4-5 Minimal
2 155-178 96-110 2-3 6-8 Moderate
3 179-210 111-130 3-4 9-12 Extensive
4 211-250 131-155 4-6 13-18 Extreme
5 >250 >155 >6 >18 Catastrophic

Click Table of Contents when finished looking at descriptions

Damage Hurricanes Cause--Winds and Storm Surges

Damage-Causing Winds

Hurricanes produce damaging surface winds and storm surges. While high winds cause significant structural and environmental damage, storm surges are frequently the most devastating element of a hurricane.

Storm Surges

A storm surge is a rise in sea level along a coastline caused by the combination of a hurricane's surface winds and the physical geography of a coastline. Surface winds above the ocean's surface push water toward the hurricane's eye, creating a mound of water. The mound of water is then influenced by the slope of the coastline as the hurricane approaches land. If the coastline is shallow, water cannot flow away from the mound and the mound grows. If the coastline is deep, water can disperse and the mound may grow slowly or disperse depending on hurricane strength. An example of a shallow-water coastline is the Gulf Coast while an example of a deep-water coastline is found in New England.

Shallow-water Coastline

Deep-water Coastline

Each of the animations above depicts surge dynamics in action. As you watch the storm-surge animations, notice the effect that the physical geography of each coastline has on storm surge. Also note the waves on top of the ocean's surface. Wind, waves, and sea-level rise all contribute to storm-surge damage

The greatest storm-surge damage is to the right of a hurricane's eye (as you face the shoreline) in the Northern Hemisphere. It occurs to the right of the eye because winds, ocean waves, and sea-level rise are all moving in an onshore direction. In contrast, to the left of the eye, ocean waves and sea-level rise are moving in an onshore direction, but the winds are blowing in an offshore direction. The offshore direction of the winds moderates the effect of the storm surge. You will explore this idea in the Explore Hurricanes section with Hurricane Opal as it comes ashore.

Why Do Hurricanes Form and Where Are They Found?

Hurricanes form and intensify over oceanic regions. They require sea-surface temperatures of at least 26°C (80°F) and the influence of the earth’s rotation to initiate a spinning circulation (Coriolis effect).

The adjacent map shows the places on earth where these conditions are met for hurricane formation. Hurricanes generally form at the tail of the arrow and typically track following the arrow to its arrowhead.

In North America, we call a storm that results from these conditions a hurricane. In other parts of the world, a hurricane is known by other names, including "typhoon" in the Western North Pacific and "tropical cyclone" in the Indian Ocean and the Western South Pacific.

What is a Hurricane?

A hurricane is an intense, rotating oceanic weather system that possesses maximum sustained winds exceeding 119 km/hr (74 mph). It forms and intensifies over tropical oceanic regions.

Hurricanes are generally smaller than storms in mid-latitudes, typically about 500 km (311 miles) in diameter. At the ocean’s surface, the air spirals inward in a counterclockwise direction. This cyclonic circulation becomes weaker with height, eventually turning into clockwise (anticyclonic) outflow near the top of the storm.