A rare weather phenomenon that affects the area only about once a decade, filled the Grand Canyon in the U.S. with a dense, white fog at the end of November. The phenomenon, known as “temperature inversion,” happens when the temperature profile of the atmosphere is inverted from its usual state, and cooler air is trapped at the earth’s surface by warmer air above.

Typically, the temperature of air in the atmosphere falls the higher up in altitude you go. This is because most of the suns energy is converted into heat at the ground, which in turn warms the air at the surface. The warm air rises in the atmosphere, where it expands and cools. When temperature inversion occurs, the temperature of air actually increases with height. The warm air above cooler air acts like a lid, trapping the cooler air and fog at the surface and preventing it from rising.

Temperature inversions happen once or twice a year, typically in the winter months. However, these inversions are partial and cover only few parts of the Grand Canyon. The most recent inversion happens only once every 10 years, because the fog filled up the entire canyon and it happened on a cloudless day.

AccuWeather.com Meteorologist Andy Mussoline explained the factors that contributed to the event.

“First, there was higher-than-normal moisture in the canyon,” he said. “There was 0.75 of an inch of liquid precipitation that fell between Nov. 20 and Nov. 24 at the Grand Canyon National Park Airport [both snow and rain]. Normal precipitation during that time is only 0.19 of an inch, which converts to nearly 400 percent of normal precipitation within about a week of the event.”

“Additionally, the average high temperature for this time of year is about 48 degrees Fahrenheit, which means there would be less evaporation of that precipitation than there would be in the summer months. This allowed more moisture to stay in the air inside the canyon.”

“A high pressure system settled into the region late last week and allowed for clear skies and calm winds, two important weather conditions that allow the air near the ground to cool rapidly,” Mussoline said. “The rapid cooling of the ground allowed a temperature inversion to form.”

The canyon from space

Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is one of the hottest places on Earth, along with deserts in the Middle East and the Sahara.

Death Valley’s Badwater Basin is the point of lowest elevation in North America, at 282 feet (86 m) below sea level. It is 84.6 miles (136.2 km) east-southeast of Mount Whitney, the highest point in the contiguous United States, with an elevation of 14,505 feet (4,421 m). On the afternoon of July 10, 1913, the United States Weather Bureau recorded a high temperature of 134 °F (56.7 °C) at Furnace Creek in Death Valley, which stands as the highest ambient air temperature ever recorded on the surface of the Earth. This reading, however, and several others taken in that period, a century ago, are disputed by some modern-day experts.

Lake Hillier is a saline lake on the edge of Middle Island, the largest of the islands and islets that make up the Recherche Archipelago in the Goldfields-Esperance region, off the south coast of Western Australia. It is particularly notable for its pink colour. A long and thin shore divides the Southern Ocean from the lake.

Lake Hillier is about 600 metres (2,000 ft) in length by about 250 m (820 ft) in width. The lake is surrounded by a rim of sand and a dense woodland of paperbark and eucalyptus trees with a narrow strip of sand dunes covered by vegetation separating its northern edge from the northern coast of Middle Island. The most notable feature of the lake is its pink colour. The vibrant colour is permanent, and does not alter when the water is taken in a container. The pink colour is considered to be due to the presence of the organism Dunaliella salina. Air is the best mode of transportation for viewing the lake. At one point in its history the lake was used to collect salt.

Lake Hillier was visited by the Matthew Flinders’ expedition on 15 January 1802. Flinders’ journal entries are considered to be the first written records of the lake. Flinders observed the pink lake after ascending the island’s highest peak (now called Flinders Peak), describing the lake as follows:

In the north-eastern part was a small lake of a rose colour, the water of which, as I was informed by Mr. Thistle who visited it, was so saturated with salt that sufficient quantities were crystallised near the shores to load a ship. The specimen he brought on board was of a good quality, and required no other process than drying to be fit for use.

Flinders visited Middle Island again in May 1803; he intended “to stop a day or two in Goose-Island Bay, for the purposes of procuring geese for our sick people, seal oil for our lamps, and a few casks of salt from the lake on Middle Island”. It is reported that Flinders subsequently named the lake after William Hillier, a crew member of Investigator who died of dysentery on 20 May 1803 prior to the expedition’s departure from Middle Island.

In 1889, Edward Andrews investigated the commercial possibilities of producing salt from Lake Hillier, and briefly moved onto the island with both of his sons. They left after working the salt deposits for about one year.

The lake was subject to salt mining during the late 19th century. The salt mining enterprise is reported as failing for a number of reasons including “the toxicity of the salt collected for consumption”.

The only living organisms in Lake Hillier are microorganisms including Dunaliella salina, which causes the salt content in the lake to create a red dye which helps produce the colour, as well as red halophilic bacteria present in the salt crusts. Despite the unusual hue, the lake exhibits no known adverse effects upon humans. From above, the lake appears a solid bubble gum pink, but from the shoreline it appears more of a clear pink hue. The shoreline is also covered in salt crust deposits.

Despite the high salt content levels (comparable to those of the Dead Sea), Lake Hillier is safe to swim in. However, there are very few ways to reach Lake Hillier. Aeroplane scenic flights are the most common method, with 6 flights a day departing Esperance Airport, flying over Lake Hillier via the nearby Cape Le Grand National Park. Cruises are also an option for passengers wanting to visit the isolated lake, and surrounding forest area.

The Odessa Catacombs are a labyrinth-like network of tunnels (subterranean cavities) located under the city of Odessa and its outskirts in Ukraine, that are mostly (over 90%) the result of stone mining, particularly coquina. The system of Odessa Catacombs consists of a network of basements, bunkers, drainage tunnels and storm drains as well as natural caves.

The Catacombs are on three levels and reach a depth of 60 metres (200 ft) below sea level. It is one of the world’s largest urban labyrinths, running up to 2,500 kilometres (1,600 mi). Parts were used as air-raid shelters during World War II. Part of the tunnels, only under the city, were turned into bomb shelters in the Cold War. Such bomb shelters supposed to be refuge for civilians in case of nuclear strike or gas attack.

In the 19th century, most houses in Odessa were built of limestone that was mined nearby. These mines were abandoned and later used, and widened, by local smugglers,[citation needed] creating a labyrinth of tunnels beneath Odessa. Stories of smugglers are part of urban legends about treasures hidden underground. Despite fairly plausible details, such stories can hardly be proven. Many of the tunnels under living areas were filled up with earth, concrete or sand by construction companies, and are no longer available.

The approximate topography of the Odessa underground labyrinth is unknown as the catacombs have not been fully mapped. It is thought that most (95–97%) of the catacombs are former coquina multilevel mines from which stone was extracted to construct the city above. The remaining catacombs (3-5%) are either natural cavities or were excavated for other purposes such as sewerage. As of 2012, there are more than 1,000 known entrances to the tunnels.

Only one small portion of the catacombs is open to the public, within the “Museum of Partisan Glory” in Nerubayskoye, north of Odessa. Other caves attract extreme tourists, who explore the tunnels despite the dangers involved. Such tours are not officially sanctioned because the catacombs have not been fully mapped and the tunnels themselves are unsafe.

The first underground stone mines started to appear in the 19th century, while vigorous construction took place in Odessa. They were used as a source of cheap construction materials. Limestone was cut using saws, and mining became so intensive that by the second half of the 19th century, the extensive network of catacombs created many inconveniences to the city.

After the Russian Revolution of 1917, stone mining was banned within the central part of Odessa (inside the Porto-Franko zone, bounded by Old Port Franko and Panteleymonovskaya streets).

During World War II the catacombs served as a hiding place for Soviet partisans, in particular the squad of Vladimir Molodtsov. In his work The Waves of The Black Sea, Valentin Kataev described the battle between Soviet partisans against Axis forces, underneath Odessa and its nearby suburb Usatove.

In 1961 the “Search” (Poisk) club was created in order to explore the history of partisan movement among the catacombs. Since its creation, it has expanded understanding of the catacombs, and provided information to expand mapping of the tunnels.

The city has a large population of over 1 million people, which some believe would benefit from the introduction of a subway system. The tunnels have been cited as the reason why such a subway system has never been built in Odessa.

Since the beginning of the 21st century limestone mining has continued in the mines located in Dofinovka, Byldynka, and “Fomina balka” near Odessa. As the result of contemporary mining, the catacombs continue to expand.

There have been various reports of people walking into the catacombs, getting lost and then eventually dying of dehydration.

Amsterdam

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Tulip fields in The Netherlands

Dubai showing the many designs of its artificial islands

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Central Park New York City

Venice

Winnipeg

The Ubari Sand Sea is a vast area of towering sand dunes in the Fezzan region of south-western Libya. But 200,000 years ago, this was a wet and fertile region with plenty of rainfall and flowing rivers. These rivers fed a vast lake, the size of Czech Republic, in the Fezzan basin called Lake Megafezzan. During humid periods the lake reached a maximum size of 120,000 square kilometers. Climate change caused the region, a part of Sahara, to gradually dry up and between 3,000 to 5,000 years ago, the lake evaporated away into thin air. Traces of this great lake still exist today in the form of micro lakes scattered among the towering dunes like wet patches in the desert. Currently there are about 20 lakes in the Ubari Sand Sea – beautiful palm-fringed oases that appear like anomalies in the harsh desert environment.

Among the most picturesque of the lakes are Gaberoun and Umm al-Maa (the Mother of Water). Located besides the ruins of the old village, Gaberoun is the one tourists mostly visit. There is a rudimentary tourist camp on the shore, including an open patio, sleeping huts, and a souvenir shop. There are two more beautiful lakes – Umm al-H’isan (the Mother of the Horse), also spelt as Oum El Hassan, located north of Gaberoun; and another one at Tarhouna, about 11km from Umm al-H’isan. These are, however, rarely visited by tourists.

The Ubari lakes are very salty. This is due to the fact that these lakes are being continuously evaporated and have no rivers replenishing them (Libya has no perennial rivers that persist year-round). This has caused the dissolved minerals in the lake waters to become concentrated. Some of these lakes are nearly five times saltier than seawater. Some take on blood-red hue from the presence of salt-tolerant algae.

Although the Ubari Lakes are not exactly shallow, ranging from 7 to 32 meters in depth, they are at the risk of drying out. The waters in Sahara’s underground aquifers, that were deposited tens of thousands of years ago in much wetter times, is limited and this is already declining thanks to the increasing use of aquifer water by growing human populations. About three decades ago the Libyan government undertook an ambitious project called Great Man-Made River, aimed at drawing water from the aquifers beneath the Fezzan region via a network of underground pipes to make the desert bloom. The project, if successful, will drain these enormous reserve of fresh water in just 50 to 100 years.

The Atlantic Ocean Road or the Atlantic Road is a 8.3-kilometer (5.2 mi) long section of County Road 64 that runs through an archipelago in Eide and Averøy in Norway.

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