Question 1261Navigation General

The correct answer is D) when air masses of different temperatures meet. A weather front exists when air masses of different temperatures and/or humidity levels meet. The boundary between these air masses is called a front, and it can be classified as a cold front, warm front, or stationary front depending on the relative motion and characteristics of the air masses. This temperature difference across the front is what creates the distinct weather conditions and potential for atmospheric instability associated with frontal systems. The other options are incorrect because they do not fully capture the definition of a weather front. Option A describes a general difference in air density, but does not specify the temperature differences required. Option B refers to the high/low pressure pattern associated with fronts, but not the temperature differences. Option C describes a situation where air masses have the same temperature, which would not result in a weather front.