1.The Earth is wrapped in a layer of gas called atmosphere. Atmosphere is tied to Earth by gravitation, so that it cannot disperse in the space. It is 500 km (300 mi) thick, being made of a mix of about 10 gases, called air. The air is made by nitrogen (78 %), oxygen (21 %) and other gases (argon, carbon dioxide, helium, neon). These are chemically inert. Others can react with different chemicals: sulfur dioxide, ammonia, methane, carbon monoxide, ozone and water vapors. There are also contaminants, like toxic gases, smoke, salt, dust and volcanic ash.
2.Atmosphere is made of 4 layers: troposphere, stratosphere, mesosphere and thermosphere.
Troposphere is the thinnest layer (12 km or 7.5 mi), but comprises 80 % of the weight of the atmosphere, being its densest layer. Planes do not fly over 9-11 km (5.5-7 mi). It is the warmest layer, because the reflected sun rays heat up the air. As we go further up into the atmosphere, the temperature decreases with 6.5oC each km (0.6 mi), reaching -55o C at the upper limit of the troposphere (called tropopause).
3.Stratosphere goes up to 50 km (30 mi) over the Earth. At its upper edge, there is the maximum ozone concentration, called the ozone belt. Here, the temperature is higher than in the troposphere, because the ozone absorbs a great amount of the ultraviolet rays. Pollution causes the destruction of the ozone belt, and, without it, the Earth would be exposed to the deadly UV light. Stratopause makes the connection between stratosphere and mesosphere.
4.Mesosphere lies between 50 to 70 km (30-42 mi) over the Earth. It is the coldest layer of the atmosphere (-90o C). This is the formation zone for ice clouds that are visible only during the sunset, when they are lighted from downwards. Usually, meteorites falling over the Earth are burned into mesosphere. Even if the air is rarer there, the resulting friction caused by meteorites choking with oxygen produces a burning temperature that destroys the meteorites.
5.The thermosphere is made of the ionosphere and magnetosphere. The air density is the lowest and this layer comprises just 0,001 % of the total volume of the atmosphere gases. The temperature increases at 500 km (300 mi) to 1,200o C.
In the ionosphere, sun radiations cause ionization: the particles are electrically charged. When the charged particles hit each other, the phenomenon of aurora borealis or aurora australis (polar lights) can be observed. The ionosphere reflects the radio waves employed in telecommunications.
Magnetosphere is located above the ionosphere, at the external limit of the Earth's magnetic field. It behaves like a giant magnet, retaining high energy particles and thus protecting the Earth. This layer has the lowest density of all, as air density gradually decreases as we go further up from the Earth.
At the upper edge of the thermosphere, called exosphere, the air has such a low density that we pass into the inter-planetary space without an evident limit.
6.Meteorological phenomena are restricted to troposphere. They are the result of the sun radiation and Earth's rotation on the atmosphere. Air currents (wind) are produced when the hot air rises up and the colder air replaces it. The Equator, where the sun shines over our head, the air is the hottest, while towards the poles the air gets cooler. The hottest place on Earth is Sahara. The highest average annual temperature is registered in Dalul (Ethiopia), in a depression located 116 m (390 ft) under the sea level: 34.4o C. At Verhojansk (Siberia), the temperature reached -70o C.
7. The biosphere is the part of the troposphere where life can exist. This goes upwards, from the Earth's surface to the maximum height where birds can fly. Through photosynthesis, plants take the carbon dioxide from atmosphere, releasing oxygen. Through respiration, plants and animals consume oxygen, releasing carbon dioxide.
As many tropical forests are destroyed, being replaced by pastures (like in South America), there are increasingly less oxygen producing trees, while the amounts of the greenhouse effect gas carbon dioxide are increasing. Thus, buying products made of tropical woods, you contribute to the global warming.
8.Atmosphere's balance is menaced by human activity, which causes greenhouse effect, global warming, air contamination, ozone belt destruction and acid rains. These effects are mainly due to the development of the industry, which took place in the last 2 centuries. The burning of the fossil fuels produces carbon dioxide, the main greenhouse effect gas. Agriculture's development dumps into the atmosphere large amounts of methane (the most powerful greenhouse effect gas) and nitrogen oxides.
9.The existing gases in the atmosphere must retain the heat (infrared rays) delivered by the sun radiation, reflecting them back to Earth. Without it, the Earth would be so cold that life would not be possible. But the gases dumped by burning fossil fuels increase this effect. By the middle of 21st century, the average temperature of the Earth is believed to be 1.5-4.5o C higher than now.
The warmer clime will melt ice stocked in the polar areas, increasing the sea level and flooding cities like New York or Amsterdam.
10.About 20 % of the Earth's population breathes severely contaminated air, especially with carbon monoxide and sulfur dioxide resulting from industrial processes. This increases the number of respiratory conditions, especially amongst children and elders. 13 % of the British children experience asthma caused by air contamination.
11.The frequency of skin cancers is increased by the thinning of the ozone layer. This is due to chlorinated hydrocarbons and fluorocarbons from aerosols, fridges, detergents and polystyrenes. These gases rise into the atmosphere and decompose into chloride ions that destroy the ozone layer. In 1985, a hole into the ozone layer was observed in Antarctica. In 1995, a similar hole was spotted into the ozone layer over the Arctic. Now, chlorinated hydrocarbons and fluorocarbons are replaced with other chemicals in the industrial processes.
12.Acid rains form when sulfur dioxide or nitrogen oxides combine in the atmosphere with water vapors, forming acids. The resulting acid rains destroy plants and animals, killing entire forests. If this acid reaches rivers or lakes, it destroys all the organisms living there.
and from this layers the ozone is the neeeded 1 for us so guys plz save this layer and stop using aerosols and CFC,s as it harms the ozone layer .makin us more prone to skin cancer save our planet earth
Liquid oxygen in an unsilvered Dewar flask. Liquid oxygen is blue.
Here are 10 interesting facts about the element oxygen. You can find more oxygen facts on the element's periodic table facts page.
Animals and plants require oxygen for respiration.
Oxygen gas is colorless, odorless, and tasteless.
Liquid and solid oxygen are pale blue.
Oxygen is a non-metal.
Oxygen gas normally is the divalent molecule O2. Ozone, O3, is another form of pure oxygen.
Oxygen supports combustion.
Oxygen is paramagnetic.
Approximately 2/3 of the mass of the human body is oxygen.
Excited oxygen is responsible for the bright red and yellow-green colors of the aurora.
Oxygen was the atomic weight standard for the other elements until 1961 when it was replaced by
Oxygen forms chemical bonds with almost all other elements, creating the corresponding oxides. For example, rust is actually the formation of iron oxide (Fe2O3) and Lime is actually calcium oxide (CaO).
Oxygen on Earth actually usually exists in the form of O2 called dioxygen, but also exists as O3, ozone, mostly in the atmosphere but also exists on the surface in smog.
The O3 in our atmosphere helps to protect the Earth from UV rays from the Sun. If the UV rays we’re able to pass through the atmosphere unhindered, life would not be able to survive. Ironically O3 on the surface is harmful to animal lung tissue
Oxygen is the 3rd most abundant element by mass in the Universe, behind Hydrogen and Helium, and the most abundant element by mass in the Earth’s crust.
O2, in liquid form and in the presence of a magnetic field, forms a magnet and has been shown to be able to form a bridge, between the two poles of a magnet, capable of supporting its own weight.
Aside from being one of the two elements that bond to form water (H2O), oxygen also dissolves into water, which is the oxygen that fish and other creatures breathe
At the present rate of creation, by photosynthesis, and consumption, by respiration and decay, the entire Earth’s oxygen is renewed every 2000 years
The bright red color of your blood is because of the oxygen attached to your red blood cells. After those red blood cells have released their oxygen and picked up a Carbon Dioxide (CO2) you blood turns a dark red, or a maroon color.
Humans inhale more than 6 billion tones of oxygen each year.
Oxygen is an element with the chemical symbol O and atomic number 8.
Windows XP happens to be one of the most popular operating systems from the Windows Family. here are some tricks that will give you a lot of extra muscle to use your Windows Machine.
1. Windows XP boasts of how long it can stay up. Whereas previous versions of Windows were coy about how long they went between boots, XP is positively proud of its stamina. Go to run and type systeminfo and you can see a lot of nice data about your Windows installation.
2. You can delete files immediately, without having them move to the Recycle Bin first. Go to the Start menu, select Run… and type gpedit.msc then select User Configuration, Administrative Templates, Windows Components, Windows Explorer and find the Do not move deleted files to the Recycle Bin setting. Set it. Poking around in gpedit will reveal a great many interface and system options, but take care — some may stop your computer behaving as you wish.
3. You can lock your XP workstation with two clicks of the mouse. Create a new shortcut on your desktop using a right mouse click, and enter ‘rundll32.exe user32.dll,LockWorkStation’ in the location field. Give the shortcut a name you like. That’s it — just double click on it and your computer will be locked. And if that’s not easy enough, Windows key + L will do the same.
4. Windows XP hides some system software you might want to remove, such as Windows Messenger, but you can tickle it and make it disgorge everything. Using Notepad or Edit, edit the text file /windows/inf/sysoc.inf, search for the word ‘hide’ and remove it. You can then go to the Add or Remove Programs in the Control Panel, select Add/Remove Windows Components and there will be your prey, exposed and vulnerable.
5. For those skilled in the art of DOS batch files, XP has a number of interesting new commands. These include ‘eventcreate’ and ‘eventtriggers’ for creating and watching system events, ‘typeperf’ for monitoring performance of various subsystems, and ‘schtasks’ for handling scheduled tasks. As usual, typing the command name followed by /? will give a list of options — they’re all far too baroque to go into here.
6. XP has IP version 6 support — the next generation of IP. Unfortunately this is more than your ISP has, so you can only experiment with this on your LAN. Type ‘ipv6 install’ into Run… (it’s OK, it won’t ruin your existing network setup) and then ‘ipv6 /?’ at the command line to find out more. If you don’t know what IPv6 is, don’t worry and don’t bother.
7. You can at last get rid of tasks on the computer from the command line by using ‘taskkill /pid’ and the task number, or just ‘tskill’ and the process number. Find that out by typing ‘tasklist’, which will also tell you a lot about what’s going on in your system.
8. XP will treat Zip files like folders, which is nice if you’ve got a fast machine. On slower machines, you can make XP leave zip files well alone by typing ‘regsvr32 /u zipfldr.dll’ at the command line. If you change your mind later, you can put things back as they were by typing ‘regsvr32 zipfldr.dll’.
9. XP has ClearType — Microsoft’s anti-aliasing font display technology — but doesn’t have it enabled by default. To enable ClearType, right click on the desktop, select Properties, Appearance, Effects, select ClearType from the second drop-down menu and enable the selection. Expect best results on laptop displays. If you want to use ClearType on the Welcome login screen as well, set the registry entry HKEY_USERS/.DEFAULT/Control Panel/Desktop/FontSmoothingType to 2.
10. You can use Remote Assistance to help a friend who’s using network address translation (NAT) on a home network, but not automatically. Get your pal to email you a Remote Assistance invitation and edit the file. Under the RCTICKET attribute will be a NAT IP address, like 192.168.1.10. Replace this with your chum’s real IP address — they can find this out by going to www.whatismyip.com, and get them to make sure that they’ve got port 3389 open on their firewall and forwarded to the errant computer.
11. You can run a program as a different user without logging out and back in again. Right click the icon, select Run As… and enter the user name and password you want to use. This only applies for that run. The trick is particularly useful if you need to have administrative permissions to install a program, which many require. Note that you can have some fun by running programs multiple times on the same system as different users, but this can have unforeseen effects.
12. Windows XP can be very insistent about you checking for auto updates, registering a Passport, using Windows Messenger and so on. After a while, the nagging goes away, but if you feel you might slip the bonds of sanity before that point, run Regedit, go to HKEY_CURRENT_USER/Software/Microsoft/Windows/Current Version/Explorer/Advanced and create a DWORD value called EnableBalloonTips with a value of 0.
13. You can start up without needing to enter a user name or password. Select Run… from the start menu and type ‘control userpasswords2′, which will open the user accounts application. On the Users tab, clear the box for Users Must Enter A User Name And Password To Use This Computer, and click on OK. An Automatic Log On dialog box will appear; enter the user name and password for the account you want to use.
14. Internet Explorer 6 will automatically delete temporary files, but only if you tell it to. Start the browser, select Tools / Internet Options… and Advanced, go down to the Security area and check the box to Empty Temporary Internet Files folder when browser is closed.
15. XP comes with a free Network Activity Light, just in case you can’t see the LEDs twinkle on your network card. Right click on My Network Places on the desktop, then select Properties. Right click on the description for your LAN or dial-up connection, select Properties, then check the Show icon in notification area when connected box. You’ll now see a tiny network icon on the right of your task bar that glimmers nicely during network traffic.
16. The Start Menu can be leisurely when it decides to appear, but you can speed things along by changing the registry entry HKEY_CURRENT_USER/Control Panel/Desktop/MenuShowDelay from the default 400 to something a little snappier. Like 0.
17. You can rename loads of files at once in Windows Explorer. Highlight a set of files in a window, then right click on one and rename it. All the other files will be renamed to that name, with individual numbers in brackets to distinguish them. Also, in a folder you can arrange icons in alphabetised groups by View, Arrange Icon By… Show In Groups.
18. Windows Media Player will display the cover art for albums as it plays the tracks — if it found the picture on the Internet when you copied the tracks from the CD. If it didn’t, or if you have lots of pre-WMP music files, you can put your own copy of the cover art in the same directory as the tracks. Just call it folder.jpg and Windows Media Player will pick it up and display it.
19. Windows key + Break brings up the System Properties dialogue box; Windows key + D brings up the desktop; Windows key + Tab moves through the taskbar buttons
