Strep throat Strep throat is a throat infection causing symptoms including a red sore throat with white patches. Hay fever Hay fever, an allergic reaction to outdoor pollens and molds, causes nasal congestion, itchy eyes, and more.
Air Density is the mass per unit volume of the air. For example, the standard air density at sea level is 1.225 kg/m 3 (0.076474 pounds/ft 3). Relative Density is the ratio of the actual air density to the standard sea level density, expressed as a percentage.
How much does air weigh? It might not seem like it, but air has weight. Anything with mass has weight, and we know air has mass because (for example) we can feel it when the wind blows. The total weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch at sea level. You don't notice this weight, however, because you are used to it. If you live in Denver, Colorado, which is at an elevation of about 5,000 feet, then about 85% of the atmosphere is above you, resulting in an air pressure of about 12.5 pounds per square inch.