How many species of fish live in the Mississippi River, in the United States?

The Upper Mississippi River is home to over 119 species of fish -- more species than are found in any of Wisconsin’s inland lakes. Favorite sport fish include walleye, sauger, largemouth bass, smallmouth bass, channel catfish, northern pike, bluegill and crappies. On the Mississippi River, you don't necessarily need a boat to catch them! The species list also includes riverine species such as catfish, blue sucker, shorthead redhorse and bigmouth buffalo that are typical of large rivers in Wisconsin as well as some ancient fish such as paddlefish, lake sturgeon and shovelnose sturgeon.

Management of the Mississippi River’s natural resources often is accomplished through interagency cooperation, especially since there are often overlapping and shared responsibilities and authorities for fish and wildlife resources. While much of the Mississippi River that borders Wisconsin is part of the Upper Mississippi River National Wildlife and Fish Refuge, Wisconsin retained title to, custody and protection of the fishery in the river and adjacent waters.

Although the Mississippi River can be intimidating for anglers, its mix of backwater lakes, running sloughs, tailwaters and main channel habitats offer spectacular fishing opportunities.

For more detailed information on fishing on the Mississippi River including maps, safety tips for boating and river habitats for fish see the Fishing and Boating on the Mississippi River guide, also available at the Wisconsin DNR - La Crosse Service Center.

Special rules, regulations and agreements apply when fishing the Upper Mississippi River. Reciprocity agreements between Wisconsin and the states of Iowa and Minnesota allow a person to fish the boundary waters on the Mississippi River providing they have a valid fishing license from one of the adjacent states.

The boundary waters area is defined by the railroad tracks that parallel both sides of the river. However, residents must possess a resident license when fishing in their own state's boundary waters. Regulations between Wisconsin and the other states differ so anglers must obey the regulations in the state they are fishing.

Credit : Wisconsin DNR 

Picture Credit : Google

What is the driest continent on Earth?

With an average precipitation of 50 millimetres (2 inches) water equivalent per annum, decreasing to lower values farther inland, the driest continent is Antarctica. More than 99% of the 14-million-square-kilometre (5.4-million-square-mile) continent is covered by the Antarctic Ice Sheet, but one of its driest areas is the extremely low-humidity McMurdo Dry Valleys – the largest ice-free region on the continent – which sit between the Transantarctic Mountains and the Ross Sea.

Antarctica is also the highest continent, with an average elevation of 2,194 metres (7,198 feet).

Due to the continent's low rainfall, the Antarctic Ice Sheet is technically the largest desert in the world, despite also being the largest single body of fresh water (most of it in the form of ice). The Sahara, meanwhile, is the largest hot desert.

The driest place overall is located in the Atacama Desert in Chile. Between 1964 and 2001, the average annual rainfall for the meteorological station in Quillagua was just 0.5 millimetres (0.019 inches).

Credit : Guinness World Records

Picture Credit : Google

Are icebergs made of freshwater?

Icebergs are large chunks of ice that break off from glaciers. This process is called calving. Icebergs float in the ocean, but are made of frozen freshwater, not saltwater.

Most icebergs in the Northern Hemisphere break off from glaciers in Greenland. Sometimes they drift south with currents into the North Atlantic Ocean. Icebergs also calve from glaciers in Alaska.

In the Southern Hemisphere, almost all icebergs calve from the continent of Antarctica.

Some icebergs are small. Bergy bits are floating sea ice that stretch no more than 5 meters (16.5 feet) above the ocean. Growlers are even smaller.

Icebergs can also be huge. Some icebergs near Antarctica can be as big as Sicily, the largest island in the Mediterranean Sea. As little as one-eighth of an iceberg is visible above the water. Most of the mass of an iceberg lies below the surface of the water. This is where the phrase "tip of the iceberg" came from, meaning only part of an idea or problem is known.

There are many different kinds of icebergs. Brash ice, for instance, is a collection of floating ice and icebergs no more than 2 meters (6.5 feet) across. A tabular berg is a flat-topped iceberg that usually forms as ice breaks directly off an ice sheet or ice shelf.

The ice below the water is dangerous to ships. The sharp, hidden ice can easily tear a hole in the bottom of a ship. A particularly treacherous part of the North Atlantic has come to be known as Iceberg Alley because of the high number of icebergs that find their way there. Iceberg Alley is located 250 miles east and southeast of Newfoundland, Canada.

In 1912, the Titanic, a large British ocean liner on its way to New York, struck an iceberg and sank in Iceberg Alley. More than 1,500 people drowned. Soon after the Titanic sank, an International Ice Patrol was established to track icebergs and warn ships. That patrol continues today.

Iceberg patrols now use global positioning system (GPS) technology to help locate icebergs and prevent more tragedies like the Titanic. In 1999, the National Ice Center lost track of an iceberg the size of Rhode Island. It was found drifting toward the Drake Passage, an important shipping route south of Argentina. Dr. David Long of NASA's SeaWinds science team used satellite data to track the iceberg, the first time satellite technology was used for that purpose. Since that time, the SeaWinds team has used satellites to track the world's ice.

Icebergs that drift into warmer waters eventually melt. Scientists estimate the lifespan of an iceberg, from first snowfall on a glacier to final melting in the ocean, to be as long as 3,000 years.

Credit : National Geographic 

Picture Credit : Google

How many gallons of water flow over Niagara Falls every day?

3,160 tons of water flows over Niagara Falls every second. This accounts for 75,750 gallons of water per second over the American and Bridal Veil Falls and 681,750 gallons per second over the Horseshoe Falls.

The Niagara River, and the entire Great Lakes Basin of which it is a part, is a legacy of the last Ice Age. 18,000 years ago, Southern Ontario was covered by ice sheets two to three kilometres thick. As the ice sheets advanced southward, they gouged out the basins of the Great Lakes. Then as they melted northward for the last time, they released vast quantities of melt water into these basins. Our water is “fossil water.” Less than one percent of it is renewable on an annual basis, the rest leftover from the ice sheets.

The Niagara Peninsula became free of the ice about 12,500 years ago. As the ice retreated northward, its melt waters began to flow down through what became Lake Erie, the Niagara River and Lake Ontario, down to the St. Lawrence River and on to the Atlantic Ocean. There were originally five spillways from Lake Erie to Lake Ontario. Eventually, these were reduced to one, the original Niagara Falls, at the escarpment at Queenston-Lewiston. From here, the falls began its steady erosion through the bedrock.

However, about 10,500 years ago, through an interplay of geological effects including alternating retreats and re-advances of the ice, and rebounding of the land when released from the intense pressure of the ice (isostatic rebound), this process was interrupted. The glacial melt waters were rerouted through Northern Ontario, bypassing the southern route. For the next 5,000 years, Lake Erie remained only half the size of today, the Niagara River was reduced to about 10 percent of its current flow, and a much-reduced falls stalled in the area of the Niagara Glen.

About 5,500 years ago, the melt waters were once again routed through Southern Ontario, restoring the river and falls to their full power. Then the falls reached the whirlpool.

It was a brief and violent encounter: a geological moment lasting only weeks, maybe even only days. In this moment, the falls of the youthful Niagara River intersected an old riverbed, one that had been buried and sealed during the last Ice Age. The falls turned into this buried gorge, tore out the glacial debris that filled it, and scoured the old river bottom clean. It was probably not a falls at all now but a huge, churning rapids. When it was all over, it left behind a 90-degree turn in the river we know today as the Whirlpool, and North America’s largest series of standing waves we know today as the Whirlpool Rapids.

The falls then re-established at about the area of the Whirlpool Rapids Bridge and resumed carving its way through solid rock to its present location.

Cavitation is a special type of erosion that happens at waterfalls because only at the base of waterfalls is there enough speed to produce enough bubbles close enough to rock to affect it. This is the fastest type of erosion. As the water goes over the falls, it speeds up, loses internal pressure, air escapes as bubbles or cavities. These cavities collapse when the water comes to rest, sending out shock waves to the surrounding rock, disintegrating it.

Credit : Niagara Parks 

Picture Credit : Google

What are clouds made of specifically?

Clouds are created when water vapor, an invisible gas, turns into liquid water droplets. These water droplets form on tiny particles, like dust, that are floating in the air.

You hang up a wet towel and, when you come back, it’s dry. You set out a bowl of water for your dog and when you look again, the water level in the bowl has dropped even though Woofy has been nowhere near the bowl.

Where did the missing water go? It evaporated. That means some of the liquid water in the towel or bowl changed into an invisible gas called water vapor and drifted away into the atmosphere. (Notice that “evaporated” contains the word “vapor.”)

The same thing is constantly happening with oceans, lakes, rivers, swamps, swimming pools – and everywhere water is in contact with air.

Liquid water changes into a gas when water molecules get extra energy from a heat source such as the Sun or from other water molecules running into them. These energetic molecules then escape from the liquid water in the form of gas. In the process of changing from liquid to gas, the molecules absorb heat, which they carry with them into the atmosphere. That cools the water they leave behind.

The air can only hold a certain amount of water vapor, depending on the temperature and weight of the air – or atmospheric pressure – in a given area. The higher the temperature or atmospheric pressure, the more water vapor the air can hold. When a certain volume of air is holding all the water vapor it can hold, it is said to be “saturated.”

What happens if a saturated volume of air cools or the atmospheric pressure drops? The air is no longer able to hold all that water vapor. The excess amount changes from a gas into a liquid or solid (ice). The process of water changing from a gas to a liquid is called "condensation," and when gas changes directly into a solid, it is called "deposition." These two processes are how clouds form.

Condensation happens with the help of tiny particles floating around in the air, such as dust, salt crystals from sea spray, bacteria or even ash from volcanoes. Those particles provide surfaces on which water vapor can change into liquid droplets or ice crystals.

A large accumulation of such droplets or ice crystals is a cloud.

Credit : Climate Kids

Picture Credit : Google