essential
likely
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Cloud base estimate from temp/dewpoint spread?
Plain English (default view) — short, conversational, lightly seasoned with science
🔬 Scientific / formula (revealed on click) — markdown + $$…$$ ok
📐 **Rule of thumb:** cloud base (ft AGL) ≈ **(T − Td) °C × 400** - 🌡️ **Worked example:** temp 5 °C, dewpoint 2 °C → spread 3 °C → cloud base ≈ **1 200 ft AGL** - 🛸 **Part 107 needs 500 ft clearance below clouds.** If cloud base < 900 ft AGL at your flight spot, you cannot fly. METAR gives you T/Td as `02/M01` (M = minus). Compute the spread, multiply by 400.
💡 Mnemonic / memory aid (shown on hover)
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