The Asiatic Monsoon influences the currents of the North Indian Ocean, while the currents of the South Indian Ocean are influenced by the atmospheres anticyclonic circulation.

NORTH EQUATORIAL CURRENT. During the northwest monsoon (February and March), the wind blows from the continent and aids in the development of the North Equatorial Current. The current flows from east to west; and upon reaching the east coast of Africa, a good portion turns southward, crosses the equator, and becomes the MOZAMBIQUE CURRENT. A strong countercurrent exists south of the North Equatorial Current at this same time of year. In August and September, during the southwest monsoon, the North Equatorial Cur-rent reverses and flows west to east as the MON-SOON CURRENT. At the same time, the countercurrent seems to disappear.

MOZAMBIQUE CURRENT. The Mozam-bique Current flows south along the east coast of Africa from the vicinity of the equator to about 35S, where it becomes known as the ALGUHAS STREAM.

ALGUHAS STREAM. The Alguhas Stream flows westward along the southern coast of Madagascar and joins the Mozambique Current along the east African coast. From there it flows south to the southern tip of Africa (the Cape of Good Hope), where a good portion joins up with the West Wind Drift Current.

WEST WIND DRIFT CURRENT. The West Wind Drift Current flows across the Indian Ocean to the waters southwest of Australia. Here it splits; one branch continues east along the southern coast, while the other flows northward along the western coast. This branch brings relatively cool waters to the western Australian coast and contributes to the formation of fog and low stratus clouds over the region.

In general, the following statements may be made concerning the effects ocean currents have on weather:

1. West coasts of continents in tropical and subtropical latitudes (except close to the equator) are bordered by cool waters. Their average temperatures are relatively low with small diurnal and annual ranges. There is fog, but generally the areas (southern California, Mo-rocco, etc.) are arid.

2. West coasts of continents in middle and higher latitudes are bordered by warm waters which cause a distinct marine climate. They are characterized by cool summers and relatively mild winters with a small annual range of temperatures (upper west coasts of the United States and Europe).

3. Warm currents parallel east coasts in tropical and subtropical latitudes. This results in warm and rainy climates. These areas lie in the western margins of the subtropical anti-cyclones and are relatively unstable (Florida, the Philippines, Southeast Asia).

4. East coasts in the lower middle latitudes (leeward side) have adjacent warm waters that produce a modified continental-type climate. The winters are fairly cold, and the summers are warm or hot.

5. East coasts in the higher middle latitudes have adjacent cool ocean currents, with subse-quent cool summers.

Indirectly, ocean currents also influence the location of the primary frontal zones and the tracks of cyclonic storms. Located off the eastern coast of the United States in winter are two of the major frontal zones. These zones occur where the sea-surface temper-ature gradient is steep and a large amount of tropical water is transported into the middle latitudes. This places these fronts where large amounts of energy are available. This area contrasts with the strictly cold, eastern continental United States and suggests that the development of cyclones (low-pressure centers) along these fronts may be of thermodynamic origin.

Two of the main hurricane tracks in the Atlantic also appear to be associated with warm waters. One follows the warm waters through the Caribbean, and the other follows the waters off the northern and eastern coasts of Florida and the Greater Antilles. Extratropical cyclones of fall and winter also appear to be attracted to warm waters.

Learning Objective: Describe the forma-tion of ice on the surface of the sea, and differentiate between sea ice and land ice.

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