🔍 Key Concepts

• Pressure gradient force – how air moves between high and low pressure areas • Coriolis effect – how the earth’s rotation deflects moving air • Typical west-to-east movement of weather systems in mid‑latitudes (westerlies) vs what drives individual air parcels

💭 Think About

• Think about the basic rule: if you have a region of higher pressure next to a region of lower pressure, in which direction does air naturally tend to move? • Ask yourself whether the earth’s rotation and gravity are major influences on wind and air masses, or if they can be ignored. • Consider what you know about the usual track of weather systems across North America and whether that pattern is the fundamental rule for all air movement.

✅ Before You Answer

• Verify which forces ALWAYS act on air near the surface: pressure gradient, gravity, Coriolis (rotation), and friction. • Check whether any option says a force does not act on air; be suspicious of choices that deny obvious physical forces like gravity or rotation. • Confirm that regional patterns (like typical storm tracks over North America) are not being confused with the basic physical rule of how air moves relative to pressure.