BUOYING UP THE POWER GRID

NASA - Around the world, agricultural practices have developed as a function of topography, soil type, crop type, annual rainfall, and tradition. This montage of six images shows differences in field geometry and size in different parts of the world.

NASA - Large ice shelves such as the Ross Ice Shelf on the western Antarctica coastline undergo periodic episodes of large-scale iceberg calving. In 2000, several large pieces of the shelf broke off and wandered around in the Ross Sea, breaking into several smaller bergs over the next few years. Among the survivors of the initial calving event is piece C-16. In late March 2006, C-16 worked its way northward along the coastline and plowed into the tip of the Drygalski Ice Tongue. The collision knocked loose a chunk from the tip of the ice tongue.

These images show iceberg C-16 and the Drygalski Ice Tongue before and after the collision. On March 26, the table-like C-16 was poised at the southern edge of the ice tongue, but buffered from direct contact by a small wedge of sea ice. According to scientists at the Space Science and Engineering Center at University of Wisconsin, Madison, who monitor the activity, C-16 had to overcome strong winds, known as katabatic winds, that blow down the topographic incline from the top of David Glacier (the source of the ice tongue) toward the sea. The katabatic winds would have been driving the berg toward the east, but not strongly enough to completely clear the ice tongue. The image from March 31 shows that C-16 had clipped the tip of the ice tongue, breaking off a piece. By April 3, both pieces of ice had swung around to the other side of the ice tongue.

Tree Hugger - Green Ocean Energy Ltd has announced that it has developed the Wave Treader designed to mount onto the tower of an offshore wind turbine. Each Wave Treader is rated at 500kW and can turn to face into the waves to ensure optimal power generation. (There's a video of how it works at the site)

NASA Within days of the magnitude 7.9 earthquake that shook China’s Sichuan Basin, floods became a hazard. The earthquake and its aftershocks sent earth and rock tumbling down mountains into rivers, creating natural dams behind which lakes quickly built up. As of May 19, 21 lakes had formed throughout the basin, said China Daily. This series of images shows the formation of one such lake (Yansai Lake) in Beichuan County. . .

Acquired on May 14, 2006, the top image shows the region under normal springtime conditions. Two tiny villages flank the river, the man-made surfaces regularly shaped and bright. The towns are connected by light-colored roads, which line the river on both sides and merge at a bridge where the river narrows on the right.

On May 15, 2008, three days after the initial earthquake, both the bridge and the roads it connected had disappeared under murky water. Some sections of the villages remained above the waterline, as did portions of the roads leading to the villages. The tops of trees, perhaps on slightly higher ground, formed tiny islands near the shores of the growing lake.

Formosat-2 took the final image on May 19, 2008. By this time, water levels in the earthquake lake had risen enough to immerse both villages and the entire road network. Tan debris floats on the surface of the water, concentrated over the locations of the villages.

Earthquake-created dams present a dual danger. Apart from the upstream floods that occur as a lake builds behind the natural dam, the piles of rubble that form the dam may be unstable. Another quake or simply the pressure of water behind it could burst the dam, sending a wall of water downstream. Downstream floods may also occur when water begins to cascade over the top of the dam. Thousands of people were evacuated from Beichuan on May 17 when one such lake threatened to burst, said China Daily.

NASA - Tucked into a pocket between the Canadian provinces of New Brunswick and Nova Scotia, the Bay of Fundy is famous for dramatic differences between its high and low tides. In fact, the tides observed here are tied with Ungava Bay (located farther north) for the largest tides on Earth. Under typical conditions, high tide at the head (the most inland part) of the Bay of Fundy is as much as about 56 feet higher than low tide.

The large tides in the Bay of Fundy result from tidal resonance. Tidal resonance occurs when the amount of time it takes a large wave to travel from the mouth of a bay to the far shore and back to the mouth is the same, or nearly the same, as the time between the high and low tides. This coincidence means that the general sloshing of the water around the bay can become synchronized with the lunar tides, amplifying their effect. When other factors come into play, such as storm surges, the tides in the Bay of Fundy have exceeded 20 meters. MORE

NASA - On May 23, Flight Engineer Jeff Williams from International Space Station Expedition 13 took this picture of the Cleveland Volcano in the Aleutian Islands. A bank of fog is a common feature around the islands. Two hours later, the plume had completely detached from the volcano The AVO reported that the ash cloud height could have been as high as 20,000 feet above sea level. Cleveland Volcano, situated on the western half of Chuginadak Island, is one of the most active of the volcanoes in the Aleutian Islands, which extend west-southwest from the Alaska mainland. It is a stratovolcano, composed of alternating layers of hardened lava, compacted volcanic ash, and volcanic rocks.