Wind

Measurements Impacts Beyond the Gulf References

What is wind?

Global winds

Wind is the movement of air caused by Earth's air temperatures and rotation. Without landmasses, the wind basic pattern would look like the model at left. Of course, continents create their own weather systems and thereby complicate wind patterns. Globally, winds move to regulate Earth's temperature: cooler air flows towards the equator and warmer air flows towards the poles.


Gulf of Maine wind

Sea winds

The Gulf of Maine, and most of the continental U.S., is located in the northern band of Westerlies between 30°N and 60°N. This is why weather typically moves from west to east across the U.S.

Gulf of Maine winds vary dramatically over seasons. In summer, the gulf typically experiences weak winds from the southwest or southeast. These summer winds bring warm, moist air that can contribute to fog formation. Autumn winds are usually out of the north-northwest. Winter and spring storms, of course, have strong winds. A familiar Gulf of Maine storm is the "nor'easter." "Nor'easters" are characterized by the high winds that blow out of the northeast just ahead of the low pressure storm (see image at right). Along with the rain or snow that "nor'easters" bring, high winds can produce strong waves that contribute to flooding and beach erosion.

Another ocean hazard is storm surge: high sea level along a coast caused by storms. The severity of storm surge events depends on coastline shape, nearshore depth, wind strength and wind direction relative to the coastline. When a storm approaches the coast, wind on one side of the low pressure center may blow water toward shore, raising sea level; on the opposite side of the storm, sea level may drop as winds blow water away from the shore. Storm-related alongshore winds have a much lesser effect on sea level.

What does GoMOOS measure?

GoMOOS instruments measure wind speed and direction at 4 meters above sea level. Wind speed and direction (expressed in compass degrees) are measured for 8 minutes. These speeds and directions are then averaged to obtain that hour's readings. GoMOOS buoys also measure wind gust, or the maximum wind speed during the observation period. Wind speed and wind gusts are expressed expressed in knots, miles per hour (mph) and kilometers per hour (kph).

GoMOOS buoy measurements are complemented by remote sensing data obtained from NASA's SeaWinds instrument on the QuikSCAT satellite. SeaWinds measures the speed and direction of surface winds in the gulf twice per day. The image above shows wind speed and direction during typical winter storm conditions in the Gulf of Maine (24 January 2000).

Impacts of wind

Winds play in key role in many processes, including:

Beyond the Gulf: What causes the wind to blow?

Air temperature varies roughly with latitude. Why? In the tropics, the sun's rays hit Earth's surface directly; however, at higher latitudes these rays hit Earth's surface at an angle and spread over a relatively large area; this, coupled with seasonal variation in daylength at higher latitudes, is why air temperature is warmer at the equator than at the poles.

Warm air rises at the equator and turns toward the poles, but it is deflected by the Coriolis force. At about 30°N and S, the cooled air descends and again is turned by the Coriolis force to create the Trade Winds and the Westerlies. At about 60°N and S, warm air from the Westerlies meets the cold Easterlies from the poles and the warmer air rises and is forced back toward the equator or to the poles. Of course, this is an idealized pattern that is complicated by the reality of continental landmasses.

When wind blows toward the east, why is it called a Westerly?

Winds, unlike currents, are named for the direction from which they are coming. For example, if you were sailing in the Gulf Stream off of Delaware, you might experience westerly winds while traveling east with the current.

References