| | Teachers' Domain: Earth System: El Niño's Influence on Hurricane Formation |
 | | Hurricanes can originate over warm tropical oceans when one of three scenarios exist: (1) ripples indicating instability develop in the easterly trade winds; (2) mid-latitude weather systems intrude into the tropics; or (3) low pressure areas form where the trade winds of the northern and southern hemispheres converge, or meet. |
 | | As a result, hurricane activity generally increases in the Pacific basin, especially in the South Pacific, the central North Pacific near Hawaiʻi, and the western North Pacific between 160° East longitude and 180° East longitude (the International Dateline). |
 | | In 2004 and 2005, the Atlantic hurricane season was very active, but 1997 — an El Niño year — experienced relatively few hurricanes compared with the long-term average, and those that did form were weak and short-lived. |
| www.teachersdomain.org /resources/ess05/sci/ess/watcyc/eshurricane/index.html (563 words) |