Explanation:

Calm weather and intense rain and hail phenomena can occur when very warm and humid air is rising over a mass of a very cold air. Warm air can hold more water than cool air. But if the air (warm or cool) is holding half as much moisture as it can hold when saturated, the relative humidity is 50 percent. Meteorologists, in contrast, use dewpoint temperature as a measure of the moisture content of air. Cold weather, and particularly cold air, can play havoc with your lungs and health. ... Cold air is often dry air, and for many, especially those with chronic lung disease, that can spell trouble. Dry air can irritate the airways of people with asthma, COPD or bronchitis.