La Nina, El Nino
The wild ways of weather
March 21, 2001
Web posted at: 3:21 PM EST (2021 GMT)
By Christy Oglesby
CNNfyi
(CNNfyi) -- You headed to homeroom in a hefty jacket and a hat. Now school's out, it's 25 degrees warmer and besides lugging a backpack, you're packing a parka.
What's that about?
A layman would just say it's the wild way of weather. A climatologist like George Taylor would say it's all about moisture in the air. The more water there is in the air, the smaller the daily temperature change. Drier air means more variation. Both are right.
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The nature and number of the factors that affect weather keep meteorologists guessing. Elevation, latitude, distance from the ocean, ocean temperature, moisture and air mass movement determine weather in a specific area, said Taylor, Oregon's climatologist. And with such mutable ingredients, it's no wonder that weather remains understandably unpredictable.
Effect of factors
Some factors have a greater effect on climate, while others affect weather more. And if you're not sure about the difference in the two, Taylor makes it plain. "Climate is what you're supposed to get," he said. "Weather is what you get. Or, climate tells you what to buy, and weather tells you what to wear."
Scientifically speaking, weather is the atmospheric conditions at a certain time and climate is a long-range, assessment or pattern of weather.
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'Climate is what you're supposed to get; Weather is what you get'
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— Climatologist George Taylor
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Elevation, latitude and distance from the ocean heavily influence climate. Moisture, ocean temperature and movement of air masses have more of an effect on daily conditions.
The further you move from the Earth's surface, air pressure is lower and temperatures are cooler. "Moving upwards a few thousand feet is like moving hundreds of miles closer to the poles," Taylor said. "The temperature drops about 5 degrees Fahrenheit for every 1,000 feet you go up."
Both poles are cold deserts, but the area near the equator is wet and warm. So latitude affects a location's temperature and precipitation. Distance from the ocean and ocean temperature affect temperature on land because of winds that emanate from over the water. The maritime polar and maritime tropical air masses usher in cold and warm air respectively.
Little boy, little girl
Weather extremes -- such as hurricanes, flooding, droughts and heat waves -- are the effects of La Nina and El Nino, Taylor said.
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La Nina, which is Spanish for 'the little girl', is an event characterized by unusually cold ocean temperatures in the Equatorial Pacific. During La Nina events, the southern portion of the United States gets less rain. And during the winter, the southeast is warmer than normal and the northwest is colder than usual. La Nina events also produce more hurricanes.
During El Nino (little boy), there are fewer hurricanes. El Nino is characterized by warmer than normal ocean temperatures in the Equatorial Pacific. That phenomenon spawns increased rainfall across the area of the United States and has caused destructive flooding. In the western Pacific regions and Australia, El Nino has caused severe droughts.
Generally, El Nino and La Nina occur in periods of 20 to 25 years, Taylor said, where you have one occurring more than the other.
Regional risks
The conditions that create severe weather expose areas to specific peril. The Midwest is more susceptible to tornadoes, and coastal regions along the Atlantic are more prone to hurricanes.
Tornadoes are affected by air masses. When three air masses -- maritime tropical, continental tropical and continental polar -- converge, tornadoes are more likely to occur. And the Midwest is where those masses are most likely to meet.
Hurricanes gather energy from warm ocean water, which is why they develop in the Caribbean and along the Atlantic coast, putting states like Florida, Georgia, Louisiana and the Carolinas in the path of their destructive forces.
| WHAT DOES IT MEAN?
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climatologist:
| person who studies the climate, which is the average course or condition of the weather in a place during a period of years, and the effect of those conditions on the natural environment
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variation:
| range in which things differ
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meteorologists:
| people who study the Earth's atmosphere and the phenomena that generate the weather
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elevation:
| height above the level of the sea; altitude
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latitude:
| distance north or south from the Earth's equator
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air mass:
| large body of air that has taken on the temperature and humidity characteristics of its region
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mutable:
| able to be changed
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air pressure:
| the weight of air above a particular point per unit area of the column of air above a particular point
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emanate:
| originate
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droughts:
| long period of dry weather brought about by excessive removal of water from the land through evaporation or human usage
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peril:
| danger
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susceptible:
| vulnerable
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La Nina brings long, hot summer
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RELATED SITES:
The Tornado Project
National Weather Service
National Hurricane Center
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