Final answer:
ENSO consists of alternating warm and cool phases known as El Niño and La Niña, characterized by changes in sea-surface temperature and air pressure in the Pacific Ocean, which have significant effects on global weather patterns.
Step-by-step explanation:
ENSO, or the El Niño Southern Oscillation, refers to a systematic shift in atmospheric pressure, sea-surface temperature (SST), and ocean circulation in the tropical Pacific Ocean. ENSO consists of two phases: El Niño, the warm phase, and La Niña, the cool phase. Anti-phasing refers to the phenomenon where these phases oscillate between high SST and low air pressure in the eastern Pacific during El Niño and the opposite conditions during La Niña.
During the El Niño phase, there's a development of warmer waters in the central and east-central equatorial Pacific Ocean, leading to high air pressure in the western Pacific and low air pressure in the eastern Pacific. Conversely, La Niña features below-average SSTs in the eastern Pacific and an air pressure pattern that is the reverse of El Niño's. ENSO cycles have a profound impact on global temperature and rainfall patterns, particularly in the southern hemisphere.