# അറ്റ്മോസ്ഫിയർ (യൂണിറ്റ്)

അറ്റ്മോസ്ഫിയർ (യൂണിറ്റ്) പ്രമാണ അറ്റ്മോസ്ഫിയർ (ചിഹ്നം: atm) മർദ്ദത്തിന്റെ ഏകകമാണ്. ഇത് 101 325 Pa (1.013 25 bar) എന്ന് നിർണയിച്ചിരിക്കുന്നു. ചിലപ്പോൾ ഇതിനെ അവലംബമായോ പ്രമാണിക മർദ്ദമായോ ഉപയോഗിക്കുന്നു.

## മർദ്ദ ഏകകങ്ങളും സമമൂല്യങ്ങളും

Pressure units
പാസ്കൽ Bar Technical atmosphere Standard atmosphere Torr Pounds per square inch
(Pa) (bar) (at) (atm) (Torr) (psi)
1 Pa ≡ 1 N/m2 10−5 1.0197×10−5 9.8692×10−6 7.5006×10−3 1.450377×10−4
1 bar 105 ≡ 100 kPa

≡ 106 dyn/cm2

1.0197 0.98692 750.06 14.50377
1 at 0.980665×105 0.980665 ≡ 1 kp/cm2 0.9678411 735.5592 14.22334
1 atm 1.01325×105 1.01325 1.0332 1 760 14.69595
1 Torr 133.3224 1.333224×10−3 1.359551×10−3 1.315789×10−3 1/760 atm

≈ 1 mmHg

1.933678×10−2
1 psi 6.8948×103 6.8948×10−2 7.03069×10−2 6.8046×10−2 51.71493 ≡ 1 lbF /in2

A pressure of 1 atm can also be stated as:

≡1.01325 bar
≡ 101325 pascal (Pa) or 101.325 kilopascal (kPa)
≡ 1013.25 millibars (mbar, also mb)
≡ 760 torr[n 1]
≈ 760.001 mm-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available[n 2][n 3]
≈ 29.9213 in-Hg, 0 °C, subject to revision as more precise measurements of mercury’s density become available[n 3]
≈ 1.033 227 452 799 886 kgf/cm²
≈ 1.033 227 452 799 886 technical atmosphere
≈ 1033.227 452 799 886 cm–H2O, 4 °C[n 2]
≈ 406.782 461 732 2385 in–H2O, 4 °C[n 2]
≈ 14.695 948 775 5134 pounds-force per square inch (psi)
≈ 2116.216 623 673 94 pounds-force per square foot (psf)
= 1 ata. The ata unit is used in place of atm to indicate that the pressure shown is the total ambient pressure on the system being calculated or measured.[1] For example, for underwater pressures a pressure of 3.1 ata would mean that the 1 atm of the air above water is included in this value.
Notes:
1. Torr and mm-Hg, 0°C are often taken to be identical. For most practical purposes (to 5 significant digits), they are interchangeable.
2. This is the customarily accepted value for cm–H2O, 4 °C. It is precisely the product of 1 kg-force per square centimeter (one technical atmosphere) times 1.013 25 (bar/atmosphere) divided by 0.980 665 (one gram-force). It is not accepted practice to define the value for water column based on a true physical realization of water (which would be 99.997 495% of this value because the true maximum density of Vienna Standard Mean Ocean Water is 0.999 974 95 kg/l at 3.984 °C). Also, this “physical realization” would still ignore the 8.285 cm–H2O reduction that would actually occur in a true physical realization due to the vapor pressure over water at 3.984 °C.
3. NIST value of 13.595 078(5) g/ml assumed for the density of Hg at 0 °C

## അവലംബം

1. Scuba Diving & Other Fun Activities, The Difference Between An ATM & An ATA