Submitted by AspGuy25 t3_10k4ov8 in askscience
a_cute_epic_axis t1_j5qn7mx wrote
Reply to comment by jermdizzle in Why does hot air cool? by AspGuy25
This is how a sling psychrometer works. It has two thermometers, one which has a cloth soaked in distilled water wrapped around the bulb. This produces a "wet bulb" and "dry bulb" temperature, from which you can determine humidity, enthalpy, dew point, etc. The wet bulb will always read the same or lower than the dry bulb. If they read the same, the RH% is 100%. If they are far apart, it's closer to 0%.
jermdizzle t1_j5riwi5 wrote
Very cool. So many early (and even more modern types, like inertial and star-based navigational systems) measurement and navigational tools rely on extremely simple and primitive concepts or operations, but they produce such useful data.
a_cute_epic_axis t1_j5rl0d1 wrote
> like inertial
One method simply measures how long it takes light to go through a coil, and if the coil is rotating it will take slightly longer or shorter than if it isn't. Three coils perpendicular (orthogonal?) to each other and you know how you're moving. Run the long term results through a filter and you can determine your latitude as well.
(Technically it's two beams in each fiber going opposite directions and they compare the phasing).
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