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Formula for estimating cloud base. Explanation please

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attherubicon:
I’v see this formula in several places for estimating the height of cloud bases:

CB ≈ (T - Td)*1000/4.4

I’m puzzled by the 4.4. I would expect a number for the dry adiabatic lapse rate, but Not 4.4

sky_watcher:

--- Quote from: attherubicon on March 28, 2021, 09:38:29 PM ---I’v see this formula in several places for estimating the height of cloud bases:

CB ≈ (T - Td)*1000/4.4

I’m puzzled by the 4.4. I would expect a number for the dry adiabatic lapse rate, but Not 4.4

--- End quote ---
From the Cloud Base Calculator site:

--- Quote from: https://www.omnicalculator.com/physics/cloud-base ---The rate at which air cools is estimated at 5.4°F per 1000 feet of altitude. The dew point decreases slower - at about 1.0°F per 1000 feet. That means that per 1000 feet, the spread decreases by 4.4°F.
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attherubicon:
Thank you.

CW2274:

--- Quote from: sky_watcher on March 28, 2021, 09:55:31 PM ---
--- Quote from: attherubicon on March 28, 2021, 09:38:29 PM ---I’v see this formula in several places for estimating the height of cloud bases:

CB ≈ (T - Td)*1000/4.4

I’m puzzled by the 4.4. I would expect a number for the dry adiabatic lapse rate, but Not 4.4

--- End quote ---
The rate at which air cools is estimated at 5.4°F per 1000 feet of altitude.

--- End quote ---
Just as an FYI, known as "standard lapse rate".