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
- Determine at what altitude in meters the air pressure is twice less than on the sea level using the barometic equation that is pressure as a function of height. Given that the temperature is 288.15 K. P=P0e -Mgh/RT, where Po is the pressure at sea level, M is the molar mass of air (in kg/mol), T is standard temperature, R is universal gas constant (8.314 N.m/mol K).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_forwardThe weather channel reported that the current temperature at the town of Fairbanks Alaska is 50 °F. What is the corresponding value of this temperature on the Centigrade scale?arrow_forward
- A 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_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_forwardIn a hurricane, the mean sustained wind velocity v (in meters per second) can be modeled by v(p) = 6.31013-p, where p is the air pressure in millibars at the center of the hurricane. Estimate the air pressure, p, at the center of the hurrican when the mean sustained wind velocity, (v(p)), is 60 meters per second. Round to the nearest hundredth. mbar Blank 1:arrow_forward
- Assume that the composition of the earth’s atmosphere is constant below an altitude of 100 km and according to Barometric equation, the pressure decreases with altitude and the atmosphere has a uniform temperature of 25°C. Calculate the barometric pressure in Pa at Mount Ağrı, for which h = 5137m (g = 9.80 m/s2). Assume that 80% of the air is nitrogen and 20% is oxygen.arrow_forwardDevices like Fitbits determine whether you have climbed stairs by determining when the atmospheric pressure changes while you are walking. By what percentage should the atmospheric pressure change when you climb a flight of stairs? You may assume the atmosphere is entirely nitrogen and that the temperature is 25 degrees celsius, and that the flight of stairs is 10 feet elevation change in total.arrow_forwardA person who is 6 feet and 3 inches tall and weighs 185 pound force ( lbf ) is driving a car at a speed of 65 miles per hour over a distance of 25 miles between two cities. The outside air temperature is 80° F . Let us convert all of the values given in this example from U.S. Customary units to SI units.arrow_forward
- At 26.0 m below the surface of the sea (density = 1 025 kg/m3), where the temperature is 5.00°C, a diver exhales an air bubble having a volume of 1.10 cm3. If the surface temperature of the sea is 20.0°C, what is the volume of the bubble just before it breaks the surface in centimeters?arrow_forwardThe temperature and humidity in the valley in the early afternoon were 29 °C and 30%, respectively. Later, dry winds sweeping across the valley carried away 4.0 grams of water vapor from each cubic meter of air. The temperature during at that time had increased to 32 °C. What was the humidity (in %) then? Humidity vs Temperature Table is below: (°C) (g/ur) 10 9 16 13 21 18 24 22 29 30 32 35 14.3 16.7 12.3 O 16.0 O None of thesearrow_forwardImagine that you have air in a sealed glass container that has a volume of 1 liter. The pressure inside the container is 1013 hPa and the temperature is 20◦C. You now inject cloud droplets into the chamber without letting any air leak out. The droplets have a radius of 10 micrometers, and you inject a concentration of drops that is typical of what you find in a cloud (200 drops per cm3). Will there be a change in the gas pressure? If so, by what amount? Please provide a calculation. What does your answer tell you about the presence of particles in the atmosphere and their potential influence on pressure?arrow_forward
- An Introduction to Physical SciencePhysicsISBN:9781305079137Author:James Shipman, Jerry D. Wilson, Charles A. Higgins, Omar TorresPublisher:Cengage Learning