Question

1. Assume that a parcel of air is forced to rise up and over a 3000-meter-high mountain as shown below. The intitial temperature of the parcel at sea level on the windward side is 35°C, and the (LCL) of the parcel is 2000 meters. The DAR is 10°C/1000 meters and the SAR is 6°C/1000meters. Assume that the condensation begins at 100% relative humidity and that no evaporation takes place as the parcel decends. Refer to Lab 16 (pages 93-95)- 10 points3000 meters2000 meters1000 metersWindSea Levela. What is the temperature of the parcel of air at the following elevations as it rises up the windward side of the mountain: 1.1000 m___2. 2000m___ 3. 3000m___b. What is the temperature of the parcel of air at the following elevations as it decends down on the leeward side of the mountain: 4. 2000 m___ level 5. 1000 m___ 6. At seac. Above the LCL the rising air will begin cooling at the___ (dry or saturated) adiabatic rate?d. At 2000 m, is the relative humidity of the parcel of air 100%? YES or NO (circle one) e. What is the source of heat energy as it decends down on the leewardside? f. Which side has the warmer temperature____(winward or leeward)?

Answer 1

An air parcel at 35°C rising over a mountain cools at the dry adiabatic rate until the LCL is reached, then cools at the slower saturated adiabatic rate due to condensation. As it descends on the leeward side, it warms adiabatically without moisture addition, resulting in higher temperatures than on the windward side.

Step-by-step explanation:

When a parcel of air with an initial temperature of 35°C at sea level is forced to rise over a mountain, its temperature will change due to adiabatic cooling. The Dry Adiabatic Rate (DAR) of 10°C/1000 meters applies until the parcel reaches the Lifted Condensation Level (LCL) at 2000 meters, where the temperature will be 25°C. Above the LCL, the Saturated Adiabatic Rate (SAR) of 6°C/1000 meters takes over due to condensation releasing heat, slowing the rate of cooling. At 3000 meters, the air parcel's temperature will be 19°C.

As the air descends on the leeward side of the mountain, it warms at the SAR without any moisture being added since no evaporation occurs. The temperature at 2000 meters will be 25°C, the same as on the windward side at the same elevation because the air has not yet returned to the dry adiabatic rate. Further down at 1000 meters, the temperature will be 31°C, and back at sea level, it will be 37°C.

Above the LCL, the rising air cools at the saturated adiabatic rate. At 2000 m, relative humidity is 100%. The source of heating during the descent is adiabatic warming from compression of the air; thus, the leeward side will have the warmer temperature.