See also: Dealing with Breathing Problems written for patients. The term hyperventilation describes excessive ventilation of the lungs, beyond what is required to achieve normal arterial blood gases.
A light frost occurs when the temperature drops to below 32 degrees Fahrenheit, and refers to the conditions that allow a layer of ice crystals to form when water vapor condenses and freezes without first becoming dew. Harvest basil and other tender herbs before a light frost (when the temperature drops to 32 degrees Fahrenheit). 2  Even if they survive the frost, they don't do well in cold temperatures. 3  The same is true for most annuals.
Surface temperature inversion layers form on long winter nights when the sky is clear and winds are calm. The ground cools quickly and becomes colder than the air above. Air in contact with the cold ground ends up colder than air above. In a temperature inversion layer, air temperature increases with increasing altitude (Point 5). This produces a very stable layer of air at ground level (stable means the air is stagnant, there are no up or down air motions). A very reasonable wintertime morning temperature profile in Tucson is shown below: