- Large mass if sinking air that produces an area of H pressure on the Earth's surface. - The source is the upper atmosphere where humidity is low. - As the dry air descends, it warms, which limits cloud development & produces dry conditions. - The isobars are far apart & weak winds blow out wards from the centre of H pressure (clockwise in N hemisphere). - Larger than depressions, giving days or weeks of settled weather (blocking anti-cyclones block the Jet Stream).
Consider a time when mars is in the middle of one of its periods of apparent retrograde motion. during this time, mars appears <u>brightest</u> in our night sky and crosses the meridian around <u>midnight</u>.
