Atmospheric pressure at sea level

Fig. 2. Vapor pressure and temperature (4), where the bold and dashed horizontal lines represent normal atmospheric pressure at sea level and at 609.6 m...

Fig. 3. Standard system of pressure measurement (3), where the bold line represents standard atmospheric pressure at sea level.

Density is the mass per unit volume kg m b The density of a fluid depends on temperature and on atmospheric pressure or a static imposed head. At stan dard conditions 20 °C and 101.325 kPa (atmospheric pressure at sea level)... 

If a column of air 1-inch square extended to the top of the atmosphere could be weighed, this column of air would weigh approximately 14.7 pounds at sea level. Thus, atmospheric pressure, at sea level, is approximately 14.7 pounds per square inch or psi. 

Atmospheric pressure can be measured by any of several methods. The common laboratory method uses a mercury column barometer. The height of the mercury column serves as an indicator of atmospheric pressure. At sea level and at a temperature of 0° Celsius (C), the height of the mercury column is approximately 30 inches, or 76 centimeters. This represents a pressure of approximately 14.7 psia. The 30-inch column is used as a reference standard. 

Before we start describing the gas law relationships, we will need to describe the concept of pressure. When we use the word pressure with respect to gases, we may be referring to the pressure of a gas inside a container or we might be referring to atmospheric pressure, the pressure due to the weight of the atmosphere above us. The pressure at sea level is 1 atmosphere (atm). Commonly, the unit torr is used for pressure, where 1 torr = 1 mm Hg (millimeters of mercury), so that atmospheric pressure at sea level equals 760 torr. The SI unit of pressure is the pascal (Pa), so that latm = 760 mm Hg = 760 torr = 1.01325 X 10s Pa (or 101.325 kPa). 

Many units are used to express pressure. Because pressure is defined as force per unit area, a common unit used in the United States is pounds per square inch. This unit is commonly used for tire inflation pressure. The atmospheric pressure at sea level is about 14.7 pounds per square inch. In the metric system, the basic unit for force is the newton, abbreviated N, and area is mea-... 

The values in column three of Table 9.2 are atmospheric pressure at sea level. At the top of Mt. Everest, the atmospheric pressure is only one-fourth of that at sea level. 

During inhalation anesthesia, the partial pressure of the inhaled anesthetic in the brain equals that in the lung when steady-state conditions are achieved. Therefore, at a given level (depth) of anesthesia, measurements of the steady-state alveolar concentrations of different anesthetics provide a comparison of their relative potencies. The volatile anesthetic concentration is the percentage of the alveolar gas mixture, or partial pressure of the anesthetic as a percentage of 760 mm Hg (atmospheric pressure at sea level). The minimum alveolar anesthetic concentration (MAC ) is defined as the... 

The pressure at P1 is now the 1-psi static head, minus the 5-psi nozzle exit loss, or negative 4 psig (or positive 10.7 psia). That is, the pressure at the drain is a substantial partial vacuum, or a negative pressure, meaning that it is below atmospheric pressure (atmospheric pressure at sea level is 14.7 psia). 

Where, then, does the available NPSH to a sump pump really come from It comes from atmospheric pressure. Atmospheric pressure, at sea level, is equivalent to... 

The pascal represents a very small pressure, and therefore the most common applications, such as tire pressure, will use kilopascals (kPa) instead of Pa. Other units of pressure include the torr (or millimeter of mercury, mmHg), inches of mercury, the atmosphere (atm), and the bar. A torr is an amount of pressure necessary to support a column of mercury 1 mm in height. One atmosphere of pressure is loosely defined by the atmospheric pressure at sea level, but is more precisely defined as the pressure necessary to support a column of mercury 760 mm in height. One bar of pressure is equal to 100 kPa. The relationships between the various units of pressure are given below ... 

Standard units apply to systems that are at standard (normal) conditions. Standard conditions include such conditions as 25°C (room temperature) and 1 atm (atmospheric pressure at sea level). 

A typical value of the atmospheric pressure at sea level, 760.0 mm Hg, has been designated as a standard pressure of I atmosphere The conversion table on the inside front cover lists equivalent values of this pressure in various units. 

The boiling temperature of nitrogen at atmospheric pressure at sea level (1 aim) is - 196 C. Therefore, nitrogen is commonly used in low lemperatnre scientific studies since the temperature ofliquid nitrogen in a tank open to the atmosphere remains constant at -196°C until the liquid nitrogen in the tank is depleted. Any heal transfer to the tank results ill the evaporation of some liquid iiiliogen. which has a heal of vaporization of 198 kJ/kg and a density of 810 kg/m at 1 atm. 

Q As temperature increases, water molecules gain kinetic energy. Vapor pressure increases (black arrows) but is less than atmospheric pressure (red arrows). o A liquid has reached its boiling point when its vapor pressure is equal to atmospheric pressure. At sea level, the boiling point of water is 100°C. 

A student pilot takes off from an airport at sea level, and flies to an airport that is 1000 ft above sea level, (a) As the pilot enters the traffic pattern 1000 ft above ground level at the destination airport, what would an air pressure gauge aboard the plane read Assume an air temperature of 15°C and an atmospheric pressure of 1 atm at sea level, (b) The plane altimeter is a gauge that senses pressure and translates the pressure value to an altitude readout. Suppose that during the flight, the atmospheric pressure at sea level in the region increases to 1.02 atm. If the pilot does not correct for this, at what altitude will he or she enter the traffic pattern ... 

Elence W decreases only very slowly at wind speeds above 50 mi / h, at least assuming that if not Eq. (14) in its entirety then at least this aspect of Eq. (14) retains at least approximate validity at Neptune-like temperatures. The singularity in (dW/dV)T at V = Omi/h is sufficiently weak that it has no effect on values of W itself.] Since standard atmospheric pressure at sea level on Earth is approximately lbar, for illustrative purposes and for argument s sake let us assume that the standard wind chill formula [Eq. (14)] retains at least approximate validity at the 1 bar level on Neptune, especially since the atmospheric density of 0.45 kg / m3 at the 1 bar level on Neptune is at least comparable to that at the 1 bar level on Earth. (We will appraise this assumption later in this Sect. 4.2, especially in the second-to-last paragraph thereof.) The temperature in Neptune s atmosphere at the 0.1 bar level is T = 55 K = — 218 °C = — 361 °F [65], Since Eq. (14) was derived for standard conditions (lbar atmospheric pressure on Earth), its accuracy may be reduced if it is applied at the 0.1 bar level on Neptune. If we nevertheless apply it at the 0.1 bar level on Neptune, we obtain, even with a slow (by Neptune standards) V = 50 mi / h wind, W = -544 °F = -320 °C = -47 K. 

One atmosphere of pressure is the average atmospheric pressure at sea level. 

What is the numerical value of atmospheric pressure at sea level Do humans notice the pressure of the atmosphere Explain. 

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