Cloud Altitude Measurement, 7 April 2018

NearSys Station is experiencing 100% overcast with nimbostratus. The image beyond shows what this cloud cover looks like.

The important part of this image to note is the bright trapizoid in the middle.

The next two thermal images show the temperature appearance of the clouds.

The bright white trapizoid is 25 degrees F. You'll notice that's three degrees warmer than the surrounding, clouds

The darker portion of the cloud is warmer, therefore lower.

The relative humidity at NearSys Station is 64% and we are getting occasional light drizzle. Therefore, I believe it's more accurate to assume a wet adiabatic lapse rate closer to 3.0 degrees per 1,000 feet.

The ground temperature, according to the thermal imager is 46 degrees. According to the weather station, the air temperature is 50 degrees and the dew point is 62 degrees.

Assuming a wet adiabatic lapse rate, the cloud height is either 6,000 feet according to the thermal imager or 4,000 feet according to the weather station. Also, the difference in height between the lower dark portion of the cloud and its brighter upper portion is 1,000 feet. This also indicates the darker portion of the nimbostratus is the lower hanging part.

The clouds are drifting at a angular speed of 0.5 degrees in 4 seconds (this was a tough measurement to make since I was using the sun as a reference. Taking the average height, I estimate the wind is blowing at 7.5 MPH at 5,000 feet AGL.