El Niño, La Nina and a Normal Year

Question 1:

El Niño, la Nina and a normal year:

a. Rainfall differences:

According to Ropelewski and Halpert (1987) during El Niño periods there are low values of southern oscillation index and this means that regions receive more rain, during la Nina periods there are high values of southern oscillation index and this means that regions receive less rain.


b. Storms:

According to Maloney and Hartmann (2000) on Atlantic hurricanes in El Nino periods there are fewer hurricanes while during la Nina years there more hurricanes


El Niño, La Nina and a Normal Year

c. Ocean circulations:

A low pressure region is developed in the Atlantic and high pressure region in Peru in a normal year and therefore trade winds flow strongly from the east to west in the pacific and therefore warm waters are carried westward, in el Niño years the low pressure region is replaced by a relatively high pressure region in the pacific and this reduces the strength of trade winds and therefore there is an accumulation of warm water in Peru, in la Nina periods results after the el Nino period whereby there is an accumulation of cold water in the pacific.


Question 2:

Accelerating rate of global warming:

1. The national climate data states that the rate of global warming is increasing and in the past

25 years this rate has changed to 2 degree census per century.

2. James Randerson also states that the sea level is rising at an accelerating rate

3. Robert Correll states that there has been an increase in the rate of glacier movement

4. Global cooling is supported by orbital forcing whereby the tilt of the earth’s axis is changing and this has reduced the intensity of sunlight and seasons.

El Niño, La Nina and a Normal Year

Question 3:

La Nina year 1995 storms

Picture retrieved from http://www.wunderground.com/hurricane/at1995.asp

El Nino year 1997:

Picture retrieved from http://www.wunderground.com/hurricane/at1997.asp

Question 4:

US tornado patterns:

a. Tornados occurrence will depend on time; in the US scientist have discovered that the peak hour of tornado occurrence is 5 pm.

b. Tornados are less likely to occur in winter and more likely to occur in spring

c. The time of the year will also affect the frequency and intensity of tornados whereby may has the most tornados followed by June.

El Niño, La Nina and a Normal Year


November, from http://iri.columbia.edu/climate/ENSO/globalimpact/TC/Atlantic/index.html

November, from Http://www.ccd.ucar.edu/lanina/report/baethgen.html

November, from http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.s html

November, from http://www.physicalgeography.net/fundamentals/7z.html

November, from http://www.wunderground.com/hurricane/at1997.asp

November, from http://www.wunderground.com/hurricane/at1995.asp