With some exceptions, an Employee is covered by the HCSO if the Employee works for an Employer covered by the HCSO and: 1  Is entitled to be paid the minimum wage; 2  Has been employed by the Employer for at least 90 calendar days; and. 3  Works at least 8 hours per week in San Francisco.
Vortex ring. Spark photography image of a vortex ring in flight. A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid or gas; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal.
What is the Polar Vortex? The polar vortex is a large area of low pressure and cold air surrounding both of the Earthâs poles. It ALWAYS exists near the poles, but weakens in summer and strengthens in winter. The term vortex refers to the counter-clockwise flow of air that helps keep the colder air near the Poles. Many times during winter in the northern hemisphere, the polar vortex will expand, sending cold air southward with the jet stream (see graphic above).