El Niño Southern Oscillation, see-sawing of air pressure over the S. Pacific
ENSO
trade winds weaken & warm water sloshed back to SA
During an El Niño year
easterly trade winds and ocean currents pool warm water in the western Pacific, allowing upwelling of nutrient rich water off the west coast of South America
During a non El Niño year
upwelling decreases disrupting food chains; N U.S. has mild winters, SW U.S. has increased
rainfall, less Atlantic hurricanes
Effects of El Niño
layer of dense, cool air trapped under a layer of warm dense air, pollution in trapped layer may build to harmful levels; frequent in Los Angeles, California and Mexico City, Mexico
Temperature inversion
Types – Surface, Crown, Ground (in order) usually burn only under growth and leaf litter on forest floor; hot fires, may start on ground but eventually leap from treetop to treetop; go underground, may smolder for days or weeks, difficult to detect and extinguish, i.e. peat bogs.
Forest Fires
