On a day when the air temperature is 85°F, the wet-bulb reading of a psychrometer is 70°F. Find each of the following: (a) relative humidity, (b) dew point, (c) maximum moisture capacity of the air, and (d) actual moisture content of the air.
(a)
Answer to Problem 5E
Explanation of Solution
Given info: The dry-bulb and wet-bulb readings of a psychrometer are
Explanation:
Wet-bulb depression is the difference in the dry-bulb and wet-bulb reading.
The expression for the wet-bulb depression is as follows,
Here,
Substitute
Refer table H.1 in Appendix H provided in the textbook to find the relative humidity.
The relative humidity of the air is
Conclusion:
Therefore, the relative humidity is
(b)
Answer to Problem 5E
Explanation of Solution
Given info: The dry-bulb and wet-bulb readings of a psychrometer are
Explanation:
Wet-bulb depression is the difference in the dry-bulb and wet-bulb reading.
The expression for the wet-bulb depression is as follows,
Here,
Substitute
Refer table H.2 in Appendix H provided in the textbook to find the dew point.
The dew point is
Conclusion:
The dew point of the air is
(c)
Answer to Problem 5E
Explanation of Solution
Given info: The dry-bulb and wet-bulb readings of a psychrometer are
Explanation:
Wet-bulb depression is the difference in the dry-bulb and wet-bulb reading.
The expression for the wet-bulb depression is as follows,
Here,
Substitute
Refer table H.1 in Appendix H provided in the textbook to find the maximum moisture capacity of the air.
The maximum moisture capacity of the air is
Conclusion:
The maximum moisture capacity of the air is
(d)
Answer to Problem 5E
Explanation of Solution
Given info: The dry-bulb and wet-bulb readings of a psychrometer are
Explanation:
The expression for the relative humidity is as follows,
Here,
Rearrange equation (1) to get an expression for the actual moisture content of the air.
Substitute
The actual moisture content of the air is
Conclusion:
The actual moisture content of the air is
Want to see more full solutions like this?
Chapter 19 Solutions
An Introduction to Physical Science
- The dry and wet bulb temperatures inside a 2500 ft² house with 8 ft ceilings are measured to be 75°F and 68°F respectively. How many gallons of moisture must be removed from the house by dehumidification to bring the humidity down to 65%, the ASHRAE 62.1 recommended maximum, while maintaining a dry bulb temperature of 75°F? 7arrow_forwardThe wind-chill index is modeled by the function W = 13.12 + 0.6215T – 11.37v0.16 + 0.3965TV0.16 where T is the temperature (°C) and v is the wind speed (km/h). When T = -19°C and v = 39 km/h, by how much would you expect the apparent temperature W to drop if the actual temperature decreases by 1°C? (Round your answers to two decimal places.) °C What if the wind speed increases by 1 km/h? ㅇCarrow_forwardConsider two identical buildings: one in Los Angeles, California, where the atmospheric pressure is 101 kPa and the other in Denver, Colorado, where the atmospheric pressure is 83 kPa. Both buildings are maintained at 21°C, and the infiltration rate for both buildings is 1.2 air changes per hour (ACH). That is, the entire air in the building is replaced completely by the outdoor air 1.2 times per hour on a day when the outdoor temperature at both locations is 10°C. Disregarding latent heat, determine the ratio of the heat losses by infiltration in the two cities.arrow_forward
- gz - Lvqi = 302525 J/kg and a total specific humidity qt = qv+qi= 16.2 g/kg. Determine its temperature T, water vapor and liquid water specific humidities. Note that in saturated air qv = qsat. Compare the virtual temperature in the cloud with the mean state. Which has the smallest air density?arrow_forwardThe following data are given for the pressure and temperature variation in air as a function of elevation: Elevation in [m] 0. Temperature in [°C]_pressure [atm] 28 1. 1000. 25 0.796 2000. 19 0.6314 3000. 12 0.4982 4000. 3 0.3905 5000. -1 0.3043 6000. 11 0.2356 You want to check if these measurements are correct. You are going to use a balloon and rise in the corresponding altitudes. If the balloon weighs 1000kg (all included, weight of yourself, equipment, inflated part etc) calculate the volume of inflated part of the balloon, so that the initial acceleration is 15m/s?. Assume that the balloon is a sphere and neglect the deflated part of the balloon as far as volume is concerned. Can you verify all measurements with this volume of the balloon? What kind of adjustments do you need to make in order to complete your mission?arrow_forward(a) Calculate the percent relative humidity on a day when the temperature is 25.0oC and the air contains 9.40 g of water vapor per m3. (b) At what temperature will this air reach 100% relative humidity (the saturation density)? This temperature is the dew point. (c) What is the humidity when the air temperature is 25.0oC and the dew point is -10.0oC?arrow_forward
- If the insolation of the Sun shining on seawater is 8.7 × 10² W/m², what is the change in temperature of a 7.0 m² by 14.0 cm thick layer of seawater at the surface in 2.0 hr? (Assume the albedo of the seawater is 0.4, the specific heat of seawater is 0.92 cal/g °C, and the density of seawater is 1.03 g/cm³.) °C AT=arrow_forwardWhat is the approximate temperature of the atmosphere at each of the followingaltitudes? 10 km, 50 km and 80km.arrow_forward(a) Calculate the percent relative humidity on a day when the temperature is 25.0ºC and the air contains 9.40 g of water vapor per m3 . (b) At what temperature will this air reach 100% relative humidity (the saturation density)? This temperature is the dew point. (c) What is the humidity when the air temperature is 25.0ºC and the dew point is – 10.0ºC ?arrow_forward
- Explain how hail forms? You need to understand that the middle part of a cumulonimbus cloud, where the air temperature is between -40° C and 0° C, there exists a combination of ice and supercooled liquid water droplets, which are cloud droplets that remain liquid even though the temperature is below the normal freezing point of liquid water. This should be part of your explanation. How large can hail get? Why are strong updrafts necessary to produce extremely large hail?arrow_forwardAn automobile moving through the air causes the air velocity (measured with respect to the car) to decrease and fill a larger flow channel. An automobile has an effective flow channel area of 3 m2 . The car is traveling at 90 km/h on a day when the barometric pressure is 70 cm of mercury and the temperature is 20°C.arrow_forwardA window has dimensions of 1.65 m by 2.4 m and is made of glass 5.25 mm thick. On a winter day, the outside temperature is 22° C while the inside temperature is a comfortable at 17° C. (k of glass =0.085W/m.K) (1.5+1.5+2 = 5marks) Calculate the following: a) the area of the window in square metres b) the temperature gradient (AT/Ax)in kelvin/metre c) the rate of heat lost through the window by conduction in wattsarrow_forward
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningUniversity Physics (14th Edition)PhysicsISBN:9780133969290Author:Hugh D. Young, Roger A. FreedmanPublisher:PEARSONIntroduction To Quantum MechanicsPhysicsISBN:9781107189638Author:Griffiths, David J., Schroeter, Darrell F.Publisher:Cambridge University Press
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningLecture- Tutorials for Introductory AstronomyPhysicsISBN:9780321820464Author:Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina BrissendenPublisher:Addison-WesleyCollege Physics: A Strategic Approach (4th Editio...PhysicsISBN:9780134609034Author:Randall D. Knight (Professor Emeritus), Brian Jones, Stuart FieldPublisher:PEARSON