Final answer:
The presence of dark clouds and low pressure indicates foul weather might be approaching. Low-pressure systems are known for causing moist air to rise and condense, leading to the formation of clouds, often resulting in precipitation and stormy conditions. Meteorologists use these indicators on weather maps to predict weather changes.
Step-by-step explanation:
Among the options provided that would indicate foul weather might be approaching, Dark clouds and low pressure are a classic sign of impending bad weather. In terms of weather, low-pressure systems occur when the earth's surface atmospheric pressure is lower than the surrounding environment. This causes moist air to rise and condense, forming clouds. As clouds gather and darken, they often indicate that a weather front is moving in, which could bring precipitation, such as rain or snow, and potentially stormy conditions. Such dynamics are evident in weather maps, where meteorologists use regions of low (L) pressure marked on weather maps to predict these conditions.
Furthermore, an important aspect of weather conditions is atmospheric pressure. High atmospheric pressure tends to lead to clear and calm weather, while low atmospheric pressure is associated with clouds and the potential for storms. The presence of strong winds and high humidity can also suggest a change in weather is imminent, possibly leading to a storm with heavy rain. Temperature changes, on the other hand, do not directly indicate approaching foul weather, nor do calm winds on their own. Therefore, the answer is option 1) Dark clouds and low pressure.