APES Test 4 Pt. 3 Midterm Review Flashcards
Lake effect
On a smaller – local or regional – scale, this effect can be seen on the shores of large lakes or bays,
In these areas, again the land warms faster than does the water during the day, so the air mass over the land rises
Air from over the lake moves in to replace it, and this creates a breeze
At night, the reverse happens: the land cools more quickly than the water, and the ari over the lake rises
The air mass from the land moves out over the lake to replace the rising air, and this creates a breeze as well
This small scale monsoon effect is called the lake effect (though effect isn’t limited to inland lakes)
Rain shadow effect
As mentioned above, the air that moves in from over the ocean or a large body of wter contains large amounts of water
If an air masss is forced to climb in altitude – if, for instance, it encounters an obstruction such as a mountain – the air will be forced to rise
When the air mass rises, it will cool, and water will precipitate out on the ocean side of the mountain
By the time the air mass reaches the opposite side of the mountain, it will be virtually devoid of moisture
El Nino
Climate variation that takes place in the tropical Pacific about once every 3-7 years, and it lasts for about on year
Under normal weather conditions, trade winds move the warm surface waters of the Pacific away from the west coast of Central and South America
As a result, the cold ocean water that lies under the displaced water moves to the surface (causing the thermocline, or line of demarcation between two layers of water with diff temperatures, to rise), bringing nutrients with it and keeping the temp of the coastal water relatively cool THIS PHENOMENON IS CALLED UPWELLING
During El Nino, the normal trade winds are weakened or reversed because of a reversal of the high and low pressure regions on either side of the tropical Pacific
Reversal of high and low pressure systems is called the Southern Oscillation
Without these regular trade winds off the Central and South American coast, the process of upwelling slows or stops, and the water off the coast becomes warmer and contains fewer nutrients
This means that during El Nino, the northern US and CAnada experience warmer winters and a less intense hurricane season; the eastern US and regions of Peru and Ecuador that are typically dry have higher than average rainfall; and the Philippines, Indonesia, and Australia are drier than normal
One environmentally important effect that El Nino has on humans is that because of the suppression of upwelling, the offshore fish populations of certain coastal areas decline
In countries like Peru, which relies heavily on fishing, El Nino has devastating economic effects
La Nina
Reverse of El Nino
Coriolis effect contributes to La Nina conditions as air moves toward the equator to replace rising hot air, the moving are deflects to the west and helps move the surface water, allowing the upwelling,
During La Nina, the surface waters of the ocean surrounding central and South America are colder than normal
The term El Nino comes from the fact that traditionally these conditions were observed to begin around Christmas time
The alternations of atmospheric conditions that lead to El Ninos and La NInas are large scale climate patterns
