In cold weather, where should you carry a compass to prevent fogging?

In cold weather, where should you carry a compass to prevent fogging?

• A. In its carrier outside outer layer of clothing
• B. Inside the outer layer of clothing
• C. Sitting on the ground in cold air
• D. Near a heater or flame

Answer: (A)

Fogging of a compass in cold weather happens when moisture-laden air from your body or breath condenses on the glass as the instrument experiences temperature changes. Keeping the compass in its carrier outside the outer layer of clothing helps minimize that condensation. The carrier protects the instrument from body moisture and reduces rapid warming when you switch from warm, humid air inside clothing to cold outdoor air, so the glass stays clearer for reading bearing directions. Carrying it inside the outer layer would trap more humidity around the compass and promote condensation when it’s exposed to the cold. Placing it on the ground in cold air exposes it to moisture and temperature shifts from the ground and wind. Bringing it near a heater or flame introduces uneven heating and extra moisture, which can also cause fogging or damage.

Fogging of a compass in cold weather happens when moisture-laden air from your body or breath condenses on the glass as the instrument experiences temperature changes. Keeping the compass in its carrier outside the outer layer of clothing helps minimize that condensation. The carrier protects the instrument from body moisture and reduces rapid warming when you switch from warm, humid air inside clothing to cold outdoor air, so the glass stays clearer for reading bearing directions.

Carrying it inside the outer layer would trap more humidity around the compass and promote condensation when it’s exposed to the cold. Placing it on the ground in cold air exposes it to moisture and temperature shifts from the ground and wind. Bringing it near a heater or flame introduces uneven heating and extra moisture, which can also cause fogging or damage.