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Posts tagged Currents

Lakes and Mountains in Apulia, Italy – June 3rd, 2009

41.4N 15.5E

June 3rd, 2009 Category: Image of the day, Lakes

Apulia, Italy - May 11th, 2009

Apulia, Italy - May 11th, 2009

This ASAR (radar) image makes it possible to observe the direction of currents in the Adriatic Sea around the coast of the Promontorio del Gargano peninsula in Apulia, Italy.

The peninsula’s mountain, Monte Gargano, is visible without geometric distortion in this orthorectified image.

Below the peninsula, the city of Foggia is visible on flatter ground, as is the city of Bari on the coast on the far right.

Several bodies of water can also be seen near the coast west of Monte Gargano, including Lake Lesina (left) and Lake Varano (right).

Lake Lesina is the ninth largest lake in Italy and the second of the southern part of the country. It is about 22 km long, an average of 2.4 km wide and covers an area of 51.4 km².

Two canals, Acquarotta and Schiapparo link it to the Adriatic Sea, from which it is separated by a dune known as Bosco Isola, between 1 and 2 km in width and 16 km in length.

Lake Varano, which is actually a lagoon, has a surface area of about 60,5 km², making it the largest coastal lake in Italy and the largest lake in the south of the country. Its depths range from 2 to 5 meters as one gradually moves away from its center.

Like Lake Lesina, it is separated from the Adriatic Sea by a very thin line of earth, which is about 10km long and 1km wide and covered with pines, eucalyptus trees and other plantlife.

Laguna Madre, Gulf of Mexico

March 23rd, 2009 Category: Snapshots

Laguna Madre, Gulf of Mexico - March 19th, 2009

Laguna Madre, Gulf of Mexico - March 19th, 2009

The Laguna Madre is the name of two long, shallow bays along the western coast of the Gulf of Mexico in the United States and Mexico; the two being separated by the outlet of the Rio Grande.

Meaning “mother lagoon” in Spanish, the Laguna Madre proper is 130 miles (209 km) long, the length of Padre Island. Its biological corridor, though, extends well into Mexico, to the mouth of the Río Soto la Marina in the state of Tamaulipas.

In the United States, the section visible here, Laguna Madre is separated from the Gulf of Mexico on the east by Padre Island, and bounded on the west by mainland Texas, and extends from Corpus Christi in the north to Port Isabel in the south.

In Mexico, Laguna Madre is separated from the Gulf of Mexico on the east by a number of barrier islands, including Barra Los Americanos, Barra Jesús María, and Barra Soto la Marina. It is bounded on the west by mainland Tamaulipas.

The Laguna Madre is very shallow, with an average depth of only 0.9 m. It is connected to the ocean by only two narrow inlets, so the tidal range – which is already minor in this part of the Gulf of Mexico – is negligible.

Oceanographically, the Laguna Madre is considered a hypersaline lagoon; this indicates that it is usually much saltier than the ocean, due to being nearly landlocked in a semiarid environment, and is one of only six hypersaline lagoons in the world. The Laguna Madre has been experiencing a persistent algal bloom (including drift algae) that may be partially caused by its hypersaline conditions, which favor algal growth.

Atmospheric effects are much more important than tides in its circulation; its weak currents generally follow the prevailing winds, and these winds can influence the water level by as much as a meter. Some such currents are visible to the South, their movements made visible by green algae.

Ice Leads in Antarctica

March 1st, 2009 Category: Snapshots

Ice melting off Antarctica coast - February 18th, 2009

Ice melting off Antarctica coast - February 18th, 2009

A network of cracks can be seen in ice in Antarctica (center right). These cracks, called leads, open when warmer conditions cause the ice to break apart, and refreeze when colder conditions are present.

The white swirls in the water are caused by ice forming in the presence of eddy-currents. These currents move in the opposite direction of normal water flow. As ice forms on the surface, it takes on the shape of the currents, making their movements visible to the naked eye.

Currents near Antarctica

February 18th, 2009 Category: Snapshots

Currents near Antarctica - February 15th, 2009

Currents near Antarctica - February 15th, 2009

Swirled patterns are visible in currents off the coast of Antarctica.

The lighter grey areas are actually ice that is beginning to form, taking on the swirled shape of the currents.

The currents themselves swirl due to eddy-currents: water flowing in the opposite direction of that of the normal currents.

Algae Makes Currents off Mexican Coast Visible

February 12th, 2009 Category: Snapshots

Algae along Mexican coast - February 7th, 2009

Algae along Mexican coast - February 7th, 2009

This stretch of the Mexican coast along the Gulf of Mexico in the states of Campeche (northeast) and Yucatan (southwest), is experiencing a phytoplankton and algal bloom.

This area had previously been observed using an image from late November, in which there was a similar amount of phytoplankton present. (Please click here to compare the images).

The algae is particularly concentrated and bright green in the Términos Lagoon. Some sediments are present along the coastline just west of the lagoon.

Further north, upon opening the full image, some interesting wave patterns can be seen, traced in the algae. The algae makes it possible to observe the water currents, usually invisible to the naked eye.