Mastering Weather Instruments Data Collection

Geography Paper 2 isn't strictly about map reading. You are guaranteed to face a section assessing your knowledge of geographical data collection, specifically surrounding weather instruments. Cambridge will regularly ask you to identify an instrument from a diagram, explain how it works, and detail how to properly site it.

If you are still finalizing your paper allocations, visit our Ultimate Geography Guide to see how heavily Paper 2 weighs on your final A* calculation.

📋 From the Desk of Robert Hughes

The Maximum-Minimum Trap: I watched a student throw away 3 marks on a simple diagram of a Maximum-Minimum (Six's) Thermometer. Cambridge asked to read the current temperature. The student read the top of the metal indices. WRONG! To read the current temperature, you must always read the bottom of the meniscus of the mercury/alcohol, not the floating metal index marker. The index marker only shows the prior maximum or minimum recorded.

The Big Four Weather Instruments

1. The Anemometer (Wind Speed)

Consists of three or four metal cups arranged on a vertical shaft. The wind catches the cups, causing them to spin. A meter at the base converts the rotations into kilometers per hour or knots. Crucial siting rule: It must be placed on a high roof or completely open area so wind is not obstructed by ground-level obstacles.

2. The Wind Vane (Wind Direction)

A pointer with a tail fin placed atop a high pole. The wind pushes the tail, forcing the arrow to point into the direction the wind is coming from. If the arrow points naturally to the South, it is a "Southerly wind".

3. The Rain Gauge (Precipitation)

A metal cylinder containing a funnel and a measuring jar. Siting is everything for rain gauges. They must be sunk partially into the ground to ensure stability, but the rim must protrude exactly 30cm to prevent rain splashing up from the ground into the funnel.

4. The Barometer (Air Pressure)

Typically an Aneroid Barometer in modern questions. Contains a flexible corrugated metal box (vacuum inside). When air pressure increases, the box is compressed, pushing a lever to move a dial pointer. Measured in millibars (mb).