Tsunamis are frequently (and inappropriately) called “tidal waves” and are a serious concern whenever an off-shore earthquake is detected. Although tsunamis are only a meter or so high as they propagate in the deep ocean, they can grow to several meters by the time they reach shore. These are typically generated by earthquakes or underwater landslides; and although rare, these are like dormant volcanoes that can shake your world up at any given time. In earthquakes, the strain energy is released and propagated away primarily in the form of p- (longitudinal) and s- (shear) waves propagating through the solid earth. If the earthquake is in the ocean, a portion of this energy is also carried by the free surface of the ocean. In this sense, the tsunami is simply one of the natural modes of vibration of the earth-ocean system.
Of course tsunamis have nothing to do with the tides driven by the gravitational forces between the earth and the moon. Thus, to call a tsunami a “tidal wave” is not only inappropriate, but is likely to lead to confusion among lay-people. By large tsunamis are just ordinary water waves and comply with the same physics as waves in your coffee cup or bathtub. However, as they are generated by geophysical forces they also have the potential to carry geophysical energy and momentum levels which can be devastating to mere humans!
One of the interesting characteristics of tsunamis is that they can travel at speeds approaching 500 mph while in the deep ocean, making it unfit for the characteristics of a wave, leave alone a tidal wave. In turn, this observation is due to the fact that the tsunamis are frequently shallow water waves, even while propagating in water they are not more than perhaps a mile deep or even more. In water of depth 4 km, you can verify that the tsunami speed is about 200 ms or 400 mph.
Occurrence of a Tsunami wave
When the tsunami approaches the shore it amplifies due to the decrease in depth. The layperson tends to associate this amplification with a conservation of mass principle. After all, the depth is getting smaller — shouldn’t the wave height get larger to “conserve mass”? Well, to surprise you even further by mentioning that this is not the case. Conservation of mass certainly holds, but this is only true for fixed masses. The wave is propagating relative to the fluid mass and such simple-minded reasoning fails. The primary principle at work is conservation of energy. Ultimately, this energy conservation law implies that the amplitude increases as h-1/4, where h is again the local water depth. This -1/4 law is referred to as Green’s law and has been known for over a century.
The general idea that waves amplify in spatially varying media (in this case, it is the depth which is varying in the direction of wave propagation), is a well-known fact in the general theory of waves and can be found in most fields of mechanics and applied physics. Perhaps the first place engineers encounter waves, which amplify when the medium varies is in elementary optics. The devastation that the tsunami wave has brought about is beyond description, it’s just a matter of minutes before everything stands washed out, rather unlike a typical tsunami wave, but definitely exceptional. Of course, the waves never attain infinite amplitude as predicted by Green’s law. These waves typically break forming a white water region known as a moving hydraulic jump or “bore”. What we observed is a figment of the Almighty’s wrath so far! Read more at Buzzle: http://www.buzzle.com/editorials/1-10-2005-63941.asp
The following are some reasons why you should quit smoking.
Money is a great motivator, and you will save tons of it if you quit smoking. It may surprise you to know that you’ll probably be able to afford a cruise from the money you’ll save in a year. A typical pack a day smoker spends over £112 a month and nearly £1,500.00 a year! You’ll also save money on dry cleaning and don’t forget that smokers pay higher health insurance premiums.
There are many obvious physical benefits of quitting smoking. Your breath and clothes will no longer smell of smoke. Neither will your teeth and fingers be stained brown with nicotine. Smoking also ages you, so quitting will help you keep the wrinkles at bay for longer. Women smokers will love that their lipstick will no longer get smudged.
Among the social benefits are that you will no longer have to go outside a restaurant for a smoke between courses. You won’t stress about whether your date is bothered by cigarette smoke or be subjected to talk about what it’s like to kiss an ashtray. You will no longer have to waste time looking for a smoking area everywhere you go. Nor will you have to pull off the road for a smoke. Also, you can say bye-bye to those nicotine fits during flights.
Health of Family
The health of your family and friends is compromised by passive smoking, which is inhaling second hand smoke that you breathe out or that your cigarettes give off. A smoker’s kids are at an increased risk of developing ear and respiratory infections. If you quit, your spouse will be less likely to develop heart disease or lung cancer. You will also save your unborn child from nicotine withdrawal.
Being able to quit smoking is a big accomplishment in itself. Other psychological benefits include, you feeling better about yourself, increased confidence, and reduced guilt. You no longer need to lie about smoking or hide the habit from your spouse, parents or children. You will be able to get rid of something that is controlling your life and be a good role model for your children.
Quality of Life
You will have an improved quality of life once you stop smoking. Food will taste and smell better. You’ll have more energy, and also stop wheezing. You can enjoy playing sports or going on hikes with your buddies without getting out of breath. You’ll also have more time, which you would have otherwise spent smoking, emptying ashtrays, searching for lighters, buying cigarettes, checking you’ve got enough, etc. Not smoking will also translate into better health that will make you less susceptible to colds and minor illnesses.
Smoking affects ones ability to procreate. If starting a family is on your agenda, it is advisable to quit. Men who smoke have a lower sperm count and more abnormal sperm than nonsmokers. Women who smoke have increased difficulty getting pregnant as compared to nonsmokers, and also have a higher rate of miscarriages during pregnancy.
Loss of Appendages
Some people who smoke regularly over a long period of time develop a disease called “peripheral vascular disease”. It causes the narrowing of the blood vessels which restricts blood flow to the hands and feet, which leads to gangrene and the eventual amputation of limbs.
The health benefits one experiences from quitting smoking are multifarious and can be experienced almost instantaneously. Within 20 minutes of quitting, your blood pressure decreases, pulse rate drops and body temperature of the hands and feet increases. After about 8 hours, the carbon monoxide level drops and the oxygen level in a smoker’s blood increases to normal. In 24 hours your chance of suffering a stroke decreases. The body’s amazing regenerative powers kicks in after just 48 hours, with nerve endings that start regrowing.
Between 2 weeks to 3 months, ones circulation improves, walking becomes easier and lung function increases. Starting from 1 month after you quit, coughing, sinus congestion, fatigue and shortness of breath decrease. A year after you quit, your excess risk of coronary heart disease is decreased to half of that of a smoker, and eventually, your stroke risk will be the same as that of people who have never smoked! Every year after you quit, your risk of developing cancer of the lungs, mouth, throat, esophagus, bladder, kidney, and pancreas decreases.
Everyone agrees that quitting is not easy. Many people encounter weight gain, irritability and anxiety in their efforts to quit, but these are short-term effects. Also, it can take several attempts before one is finally able to quit. While some stop “cold turkey”, others reduce gradually. The process can be aided by programs (even residential ones exist), counseling, medicines and products that help reduce nicotine addiction. However, be aware that the medications have side effects, so read the fine print and consult your doctor on what you should take. On an average, smokers lose 10 years of their life because of smoking. So quit right away and reclaim your life. Read more at Buzzle: http://www.buzzle.com/articles/reasons-to-stop-smoking-why-should-you-quit-smoking.html
Courtney from Study Moose
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