When are the dry-bulb and dew-point temperatures identical?

When are the dry-bulb and dew-point temperatures identical?

In some climates, cleaning the ice off the windshield of a car is a common chore on winter mornings. Explain how ice forms on the windshield during some nights even when there is no rain or snow.

A tank contains 15 kg of dry air and 0.17 kg of water vapor at $30^{\circ} \mathrm{C}$ and 100 kPa total pressure. Determine (a) the specific humidity. (b) the relative humidity, and (c) the volume of the tank.

Two airstreams are mixed steadily and adiabatically. The first stream enters at $35^{\circ} \mathrm{C}$ and 30 percent relative humidity at a rate of $15 \mathrm{m}^{3} / \mathrm{min},$ while the second stream enters at $12^{\circ} \mathrm{C}$ and 90 percent relative humidity at a rate of $25 \mathrm{m}^{3} / \mathrm{min}.$ Assuming that the mixing process occurs at a pressure of 1 atm, determine the specific humidity, the relative humidity, the dry-bulb temperature, and the volume flow rate of the mixture.