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The following are some particularly important weather related subjects which affect boaters. After all, in the marine environment, it is weather that determines the state of the waters we negotiate. Weather affects all boats, big and small, on lakes, rivers, inlets and oceans. The more we are attuned to weather conditions, the more we are able to enjoy our sport and avoid potential problems. We plan to bring you other weather related facts on this page in the future, so be sure to check back. "According to some scientists, El Niño is second to the seasons in world-wide impact." (NOAA 1994) Thanks to the availability of advanced instrumentation, meteorologists can now study the El Niño phenomenon better than ever before. And the consensus is that 1997 is a strong El Niño year. This is important to boaters because El Niño plays havoc with the normal weather patterns all over the globe. Normally, in the tropical Pacific, the trade winds blow from east to west. As they blow, warm surface waters are pushed along and piled up higher in the west than in the east. This causes an upwelling of cool waters in the east to fill the void. Rainfall is found over the warmest waters and the eastern Pacific is relatively dry. In an El Niño year, the surface temperature of the waters off Peru are higher than normal. This causes the trade winds to weaken, stop, or even reverse direction. Warm surface water is no longer pushed westward, there is no upwelling of cool, nutrient rich waters in the east and fish populations die. Since the atmosphere is in constant motion due to the rotation of the earth, the change in weather patterns in one portion of the Pacific has global consequences, causing flooding, drought, increased hurricane activity and unseasonable temperatures in various parts of the world. My husband and I encountered El Niño conditions while sailing from La Paz, Mexico to Hilo, Hawaii in 1993 (another El Niño year) aboard our sailboat. We never enjoyed the steady northeast trades which had sent us flying across the Pacific on previous voyages. Instead we encountered heavy, continuous squalls for days and, one day, an actual reversal of the trades which blew from west to east. El Niños do not occur with any regularity and the causes are not yet understood, but it is important for all boaters to watch the weather in their boating area so they will not be caught unaware and unprepared. Further information about El Niño Many boaters find comfort in a shoreline and panic when far from land. But safety in bad weather lies in deep water for several reasons. One of these is depth. In deep water, the wind makes waves unstable by exerting pressure on the crests causing the breaking crest run down the face of the wave. As water shallows closer to shore, friction with the bottom slows the base of the wave causing the crest to plunge into the sea with great force. This is what happens when waves break on a beach, but it can also occur in waters deep enough for boat navigation. The difference is much like a man running. If he is pushed on the back of the shoulders, he topples forward, but if his legs are knocked out from under him, he will plunge forward with much greater force. Therefore - when caught in heavy weather - head for safety in deeper water.
To be caught in fog on a boat out on the water can be a frightening experience. Visibility is down to zero and one wonders what and who else is out there. Fortunately there is a instrument that ought to be in wider use on boats - the psychrometer. It gauges the relative humidity in the air from which it is possible to ascertain the likelihood of fog. The most common type used on boats is a sling psychrometer. This simple, inexpensive instrument consists of two thermometers mounted together, one of which has its bulb covered with muslin. The muslin is moistened thoroughly, after which the instrument is whirled to induce rapid evaporation of the moisture. Then the two thermometers are read. The closer the reading, the greater possibility of fog. On days when fog may become a threat, taking psychrometer readings will let a boater know if it is prudent to venture out on the water or, if already out, when it becomes prudent to head for harbor. |
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