The seeds and leaves of the fennel plant both have a licorice flavor, although the flavor of fennel is milder and somewhat sweeter than anise. Fennel seeds are actually a spice, although the leaves, stalks and roots of the plant are known as a herb.
Definition of air mass. : a body of air extending hundreds or thousands of miles horizontally and sometimes as high as the stratosphere and maintaining as it travels nearly uniform conditions of temperature and humidity at any given level.
Density is the mass of air molecules per unit volume. Mass is measured by the kilogram (kg), and volume in cubic metres (m 3), so the unit of density is kilograms per cubic metre (kg m -3). We think of kilograms in terms of weight, but weight is the result of a mass subjected to gravity.