The solar hour angle Ω expresses the daily rotation of the earth. As the earth rotates 360° within 24 hours, every hour adds another 15° to the sholar hour angle. When the sun is in its highest point in the sky, the solar hour angle is zero. Angles before noon count negative, after noon positive.
As the earth rotates, the angle between the sun and due south, the solar azimuth angle, α, varies from -90° at sunrise (east) to +90° at sunset (west). Greenhinoenergy.com