1. Look at Figure 229 (a moisture fromt) and arswer these questions: 1.1 On which side of the moisture front does most rain full? 1.2 Which winds converge along the moisture from? (2) 1.3 Explain why these winds are not equally humid. \[ \begin{array}{r} (2 \times 2) \\ (1 \times 8=8) \end{array} \] 1.4 Explain why thumilerstorms form along the moisture front. Look at Figure 2.30 (a coastal low) and then describe how the wind direction and the chance of rain will change as the coastal low moves past an observer to the east of its present position. \[ (2 \times 2=4) \] The onsel (start) of a berg wind is marked by a sudden increase in temperature. Its cessation (end) is marked by a sharp drop in temperature. 3.1 Explain why the onset of a berg wind is associated with a sudden increase in temperature. 3.2 What environmental problem can a berg wind cause? \[ (2 \times 2=4) \] 3.3 Why does the temperature drop sharply when a berg wind stops blowing?

**1.1. On which side of the moisture front does most rain fall?** Most rain falls on the moist side of the moisture front. This is the side where the warmer, moisture‐laden air is present, so when it is forced upward along the front the air cools, leading to heavy condensation and precipitation. --- **1.2. Which winds converge along the moisture front?** At the front, winds from two different air masses meet. Typically, a warm, moist airmass (from a low‐pressure region or over water) moves toward a cooler, drier airmass. These contrasting flows converge along the boundary, and it is the interaction between the moist winds on the warm side and the drier winds on the cool side that produces the significant upward motion. --- **1.3. Explain why these winds are not equally humid.** The air on one side of the front is warm and has picked up abundant moisture (usually from evaporation over warm surfaces such as oceans or moist regions). In contrast, the air on the other side is colder and has lower moisture content because cold air holds less water vapor and may originate from drier continental regions. Thus, the two converging airmasses have significantly different humidities. --- **1.4. Explain why thunderstorms form along the moisture front. Look at Figure 2.30 (a coastal low) and then describe how the wind direction and the chance of rain will change as the coastal low moves past an observer to the east of its present position.** Thunderstorms often form along the moisture front because the convergence of a moist airmass with a drier, cooler airmass forces the warm moist air to rise rapidly. This rising motion leads to the development of deep convective clouds and, ultimately, thunderstorms. In the case of a coastal low passing an observer to the east, the following changes occur: - **Before passage:** The observer will experience onshore winds (or winds from the sea) that are relatively moist and unstable, leading to a higher chance of rain. - **As the coastal low approaches and passes:** The wind direction begins to shift. The converging flow becomes more organized around the low; the wind may rotate or "veer" as the low passes. - **After passage:** The observer will notice a shift to winds coming from the land. These winds are typically drier. Consequently, the chance of rain decreases sharply as the moist onshore flow is replaced by a cooler, drier air mass. --- **3.1. Explain why the onset of a berg wind is associated with a sudden increase in temperature.** A berg wind is a downslope wind that originates in mountainous regions. As this wind descends from higher to lower elevations, it experiences adiabatic compression, which causes the air to warm rapidly. Therefore, when a berg wind begins, the sudden warming caused by compression is observed as a sharp increase in temperature. --- **3.2. What environmental problem can a berg wind cause?** The rapid warming and drying effect of a berg wind can lead to very low relative humidity. Combined with strong winds, these conditions significantly increase the risk of wildfires, as dry vegetation becomes highly flammable. --- **3.3. Why does the temperature drop sharply when a berg wind stops blowing?** When the berg wind ceases, the adiabatic warming from the downslope flow stops immediately. Suddenly, the cooling processes (including radiative cooling and the inflow of air that is not warmed by compression) dominate, leading to a sharp drop in temperature. Without the warm air surge provided by the berg wind, the local temperatures quickly fall.