Salt water needs a lower temperature to freeze than pure water. The resulting ice contains much less salt than the salt water it came from. This fact has sometimes been used for desalination. Salty ice is not as strong as frozen pure water. Similarly spreading salt on ice melts it, if it's not too cold: the salt progressively eats into the ice, forming brine which does not freeze at that temperature.
Because ice floats, even large bodies of water that freeze, like some oceans, only form ice on the surface. Most lakes never freeze to the bottom. Even the coldest oceans, like the Arctic Ocean, only freeze on the top, leaving liquid ocean circulating below. Because of this the Earth's oceans are able to redistribute heat and the climate of the earth has less extremes of heat and cold than it would otherwise. If ice were to sink instead of float, the oceans would fill with ice from the bottom, would remain solid and only some of the top would thaw. A solid ocean would not circulate heat. But because ice floats on the surface the water beneath can continue to circulate and the ice on the surface stays exposed and readily melts when the temperature rises.
Big bodies of ice on land are called glaciers. Antarctica has the majority of the world's ice.
Climate change happens all the time. When it is very cold it is called an ice age. During ice ages very large areas of the earth are covered in ice, snow and glaciers. The causes of ice ages are complex, and not entirely known. Global warming is currently affecting the Earth's ice resources and its causes are also very complex.
There is also 'dry ice'; it is frozen carbon dioxide. Dry ice exposed to normal air gives off carbon dioxide gas that is odorless and colorless. The gas is so cold that when it mixes with air it cools the water vapour in the air to fog, which looks like a thick white smoke. It is often used in the theatre to make fake fog or smoke.
Travel
Travel is the activity of going from one place to another place. When a person makes the same trip every day to work or school, this type of travelling is usually called "commuting." Some people travel to other cities as part of their job. This is called "business travel." When many people travel to a distant place to stay, it is called "human migration".
Some people travel on their vacation, to visit other towns, cities, or countries. This is tourism. These people stay overnight in hotels, hostels, motels, apartments or bed and breakfast. Some prefer camping. Through the centuries, modes of travel have changed. Some people (travel writers) write about travelling in books including autobiographies or journals.
Types of travelling:
CNN
The Cable News Network (CNN) is a American cable news television channel. It was founded in 1980 by Ted Turner. The Cable News Network first aired on television on June 1, 1980. The Cable News Network's first newscast was anchored (hosted) by David Walker and his wife Lois Hart. In its first year CNN hired many political analysts, including Rowland Evans and Robert Novak. On January 1, 1982 CNN launched a 24-hour sister newscast channel with no talk shows or commentary shows called CNN2. CNN broadcasts programs from its headquarters at the CNN Center in Atlanta, or from the Time Warner Center in New York City, or from studios in Washington, D.C., and Los Angeles. CNN is owned by Time Warner, and the U.S. news channel is a part of the Turner Broadcasting System.
The hosts of its opinion shows are Don Lemon, Chris Cuomo, Fredricka Whitfield, Erin Burnett, Brianna Keiler and Brooke Baldwin.
CNN has been criticized by the right-wing Media Research Center for having a left-wing bias. According to that same Center, it is less to the left than the news divisions of ABC, NBC, and CBS. It has been criticized by Arabs for having a pro-American bias.
Leader
A leader is somebody whom people follow. A leader has authority. For people to accept a leader, his or her leadership must therefore be legitimate.
Because people follow a leader, the leader can make people do things. A leader can therefore make people work together towards a common goal.
An example of a leader is the head of government of a country. People within the government "follow" the leader, and citizens look to the head of government for inspiration and guidance. Sometimes, when a head of government lacks legitimacy, people will stop following him or her. The head of government is therefore no longer able to lead properly. This may result in a new election, or in worst case civil war.
A group with no leader is called leaderless.
Blackboard
A blackboard, also called a chalkboard, is a surface on which chalk is visible. It is used as a surface to write on. It is usually made up of wood or fiber. It is painted black to reflect the white chalks. The high-grade blackboards are made of porcelain enamelled steel.
Blackboards are often used to help in teaching in school. Blackboards are not used as much now but can be seen in some schools still. The chalk dust got everywhere, and some people are allergic to chalk dust. Now people use whiteboards: they can take modern felt-tip colour markers.
Schoolteachers use the chalkboard to display things at large. It also makes the learning cooperative between teachers and student. Chalkboards can be black or dark green, in which case they may be called blackboards and greenboards.
Linux
Linux or GNU/Linux is a Unix-like operating system (or strictly family of) for computers. An operating system is a collection of the basic instructions that manage the electronic parts of the computer allowing running applications/programs. Linux kernel (the basis of the operating system) is free software, meaning everyone has the freedom to use it, see how it works, change it, or share it.
There is a lot of software for Linux and—like Linux itself—a lot of the software for Linux is free software. This is one reason why many people like to use Linux.
The defining component of Linux is the Linux kernel, an operating system kernel that Linus Torvalds developed, at first alone. Linux is typically packaged in a Linux distribution (or "distro" for short). Distributions also include supporting system software and libraries, many of which are provided by the GNU Project.
Popular Linux distributions include Debian, Fedora, and Ubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, and include a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any purpose.
Linux was originally developed for personal computers. Linux is the leading operating system on servers such as mainframe computers, and the only O.S. used on supercomputers (at least on the TOP500 list, since November 2017). It is used by around 2.3% of desktop computers. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20% of sub-$300 notebook sales in the U.S.
Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones (especially smartphones), tablet computers, network routers, facility automation controls, televisions, digital video recorders, video game consoles and smartwatches. In fact, the Android operating system, a mobile operating system built on top of the Linux kernel, has the largest installed base of all general-purpose operating systems. In March 2017, it was reported that there were more users on Android than on Microsoft Windows, which is not based on Linux.