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The atmosphere of Earth, commonly known as air, is the layer of gases retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).
By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.
Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressure vary with altitude. Within the atmosphere, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere.Earth's early atmosphere consisted of gases in the solar nebula, primarily hydrogen. The atmosphere changed significantly over time, affected by many factors such as volcanism, life, and weathering. Recently, human activity has also contributed to atmospheric changes, such as global warming, ozone depletion and acid deposition.
The atmosphere has a mass of about 5.15×1018 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km (62 mi) or 1.57% of Earth's radius, is often used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km (75 mi). Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition.
The study of Earth's atmosphere and its processes is called atmospheric science (aerology), and includes multiple subfields, such as climatology and atmospheric physics. Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann. The study of historic atmosphere is called paleoclimatology.

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  1. D

    Do I have an air lock in my system?

    Hi, I have had this problem for a week now. The oil boiler will run for a short while and then stop. If I check the pipes around the 3 way valve they are all hot and the pump is running but all the radiators are cold. I have a bleed valve next to the water tank and I bleed that frequently and...
  2. E

    URGENT Rayburn 480K B serial no R0073699 need part number R3781 - Air Fan.

    I have a Rayburn 480K B serial no R0073699 and desperately trying to get part number R3781 - Air Fan. Waited 9 months for Rayburn to get back with availability.
  3. Dale_R

    Recent house purchase - CH/HW Major issues.

    Hi all, We recently purchased a house and nothing seems to work correctly here, I've spent weeks rectifying issues. Plumbing, electrical, carpentry it's been never ending. The house was built by Barratt Homes in the year 2000, it is a 3 bedroom house called a Palmerston, the CH/HW system is a Y...
  4. L

    Hot water pipe 'inline air release valve' - Question

    Hi, DIY homeowner here. Ist floor of house. Front bathroom hot water draws from cylinder which is heated by the Greenstar 28i Junior Combi located on the same floor. To get from cylinder to bathroom, the water goes up, horizontally over a stairhead, and back down into the bathroom. After...
  5. S

    Boiler air intake ventilation

    I have a Remeha Tzerra M 24c Plus boiler. It is sitting nice and tight, next to the central ventilation unit/pipeline of the apartment block. That central unit is rather big, I assume around 50cmx50cm and at least 20m tall. So the exhaust ventilation pipe of the boiler goes directly out to this...
  6. V

    Loosing pressure but no air in rads

    Hi..so the Baxi combi at my folks' house has lost pressure twice over a period of a couple of weeks since they started using the central heating this winter....but each time it's happened there's no air build up to be bled from any of the radiators. Am I right in thinking that the pressure drop...

    air problem with Worcester life 8000 regular

    Has anyone had any experience with the drain off/bleed valve on the primary return ,adjacent too main heat exchanger on Worcester life 8000 (45kw) regular ? I want too replace the 3/8 threaded drain off /bleed valve with a AAV ,has anymore does this? large system 28 rads 3 floors ,sealed...
  8. R

    Air lock in boiler return pipe

    I have a issue which I’m assuming is an airlock in the return pipe just above the boiler. The pipes go up and over and then enter the boiler at the bottom. The boiler fires up normally but the heat doesn’t get far and the the pipes next to the boiler make like a fluffing noise. I’m not the most...
  9. O

    What size air filter?

    Hi all, Just bought a new place that has a heat pump model # AHV42D3XH21CC I can not locate an owner manual online anywhere and wondering if anyone else can help. The previous owner also had a 20x23x1 air filter in it but I can not locate these? Was this the correct filter size as this does...
  10. A

    Samsung Air Source Heat Pump

    My ASHP has been set to 55 degrees C for the legionella in the control panel but I thought it had to be set to 60. Engineer seemed to think this is ok. I note that in 6 weeks I have had error E919 which is telling me the unit couldn't perform the correct heat for legionella thus the error code...
  11. J

    Air admittance valve below toilet

    Hi, I am installing a new en-suite toilet upstairs in a new location , the soil stack is installed by my builder going downstairs directly and into the ground where the main sewers are. He’s installed the air admittance valve on the floor below , which is slightly below where the toilet is...
  12. K

    Air to Air heat pump

    Has anyone installed / worked with air-to-air heat pumps? I wonder if their running cost is also high? There’s no information on running cost and even the people handling the funding pots for Air source heat pumps, are not aware of the costing.
  13. D

    How do I bleed a boiler with air in it?

    Hi I have drained my system to install a magnet filter on the boiler inlet and put some x400 into the system to leave for a few weeks to combat some growing sludge. After draining it and then refilling and bleeding the radiator floor by floor from the top floor down the boiler has air in it...
  14. J

    Problems with air entering central heating system

    Air entering central heating system and hot water pumping over into make up tank in artic when h/c control is switched on. There is no problem when only c/h is on! this situation as only occurred since replacing my Grundfos UPS2 with a UPS3 I have tried the pump on different speeds . On the box...
  15. J

    Air in central stem when hot water is switched on

    Replaced Grundfos Ups 2 C/H pump with a Ups3. when c/h only on no problem as soon as h/w is on as well gurgling and air in system experienced, also hot water coming out of 22mm vent into expansion tank ( doesn't happen when only c/h is on) so bad that h/w must be turn off. I had no problem...
  16. G

    New Eco 7 Cylinder - spluttering/air in system?

    We've just had a new Economy 7 cylinder put in and after 3 or 4 days we still seems to get spluttering out of the taps as thought there is air in the system Basic setup as follows - apologies for poor terminology as i'm not a plumber! Cold water tank in loft of bungalow feeds into the hot water...
  17. S

    Is this an air separator?

    Hello, I have been sent this and they said it’s leaking near the top. Am I right in thinking this is an air separator and the top is leading up to the vent pipe of F&E tank? All the ones they seem to sell look totally different. Thanks
  18. T

    Air admittance valve

    Hello, DIY plumber here, I’m after some advice regarding an AAV, my current one goes though the loft and the roof with a vent on, iv seen on some pan connectors have 32mm air admittance valves built on to them. Does this mean I don’t need the 110mm pipe into the loft at all? TIA Tom
  19. S

    Air in towel radiator

    Our upstairs towel radiator keeps filling with air at the top. We had a new system boiler, new tank and new pipework fitted in October. The new tank is in the garage which is underneath the house and the new boiler is in the kitchen at ground floor level. We also had underfloor heating installed...
  20. S

    Air in towel radiators

    Air keeps collecting in our upstairs bathroom towel radiator. Do we have a leak or what could be the cause please? We had a new system boiler and tank installed and all new pipework. The 3 towel radiators are on a separate system to the radiators in the other rooms. The tank is in the garage...
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