S-290 Final A And B Exam With Verified Questions and Answers As air sinks, it. - Increases in pressure, warms and compresses. As air sinks, it. - Increases in pressure, warms and compresses. Why do dry climates usually have lower nighttime temperatures than humid climates? - Because there is less water vapor in the air to absorb and reflect heat back to the surface at night. Why do dry climates usually have lower nighttime temperatures than humid climates? - Because there is less water vapor in the air to absorb and reflect heat back to the surface at night. T/F On average the RH doubles with each 20F decrease of temperature, or halves with each 20F increase in temperature. - True T/F On average the RH doubles with each 20F decrease of temperature, or halves with each 20F increase in temperature. - True T/F The lowest RH occurs with the highest temperature. - True T/F The lowest RH occurs with the highest temperature. - True T/F RH is usually lower on north aspects. - False T/F RH is usually lower on north aspects. - False T/F Cloudiness has little affect on relative humidity and temperature. - False T/F Cloudiness has little affect on relative humidity and temperature. - False T/F The type of vegetation has little affect on temperature and humidity. - False T/F The type of vegetation has little affect on temperature and humidity. - False T/F RH measures the amount of moisture in the air. - True T/F RH measures the amount of moisture in the air. - True S/U Clouds form in layers. - Stable S/U Clouds form in layers. - Stable S/U Gusty winds - Unstable S/U Gusty winds - Unstable S/U Smoke column spreads out after limited rise. - Stable