Ground and Sky Thermal Observation during an Inversion, 27 December 2017

At 8:10 AM MST this morning, I made a thermal observation of the sky and ground at NearSys Station. Currently, the Treasure Valley, especially the lower or western valley is under an inversion. Our sky is completely overcast and we have mild fog.

Interesting how the featureless sky above is not featureless in thermal infrared. The coldest ground temperature is 5 degrees F. The sky is 8 degrees, except in patches that are 3 degrees colder. I believe these are cloud regions that are hanging lower that our overcast.

The sky looks featureless in visible light.

The overhead stratus clouds are 3 degrees warmer than the ground.

Except in patches that are as cold as the ground.

Ground and Sky Thermal Observation for NearSys Station, 25 December 2017

With snowfall in the ground, the coldest ground temperature was 6 degrees F. The overhead stratocumulus had a temperature of 1 degree F. Assuming a dry adiabatic lapse rate of 5.4 degrees per thousand feet, the cloud base has an altitude of 900 feet.

Furthermore, the clouds drifted 10 degrees towards the east in 31 seconds. The estimate of 10 degrees was made by looking at the width of my fist from my extended arm. Using the definition of the tangent, I calculated that the clouds drifted 0.176 of their 900 foot altitude in 31 seconds.

Assuming an altitude of 900 feet, the wind speed is 3.5 miles per hour towards the east at that altitude.

Thermal infrared image of the overhead stratocumulus.

Visible image of the overhead straticumulus clouds.

Visibility for NearSys Station, 25 December 2017

Three inches of snow fell at NearSys Station in the last 24 hours. At 10:45 AM MST, measurements from the UAVSonde indicate the visibility is 30 about miles.

Looking East.

Looking North.

Looking South.

Looking West.

Sunspots for NearSys Station, 23 December 2017

NearSys Station briefly experienced mostly clear skies. Not bad after one inch of snowfall. Three tiny sunspots were visible. However, their small size and the partial cloudiness covering the sun made impossible to photograph them with a call phone camera.

The three sunspots are located close to each other in the lower left quadrant.

Visibility for NearSys Station, 23 December 2017

It snowed last night and this morning. So after shoveling snow, I sent the UAVSonde up to collect images. Visibility was good and there was no air traffic.

Based on the images returned by the UAVSonde, the visibility is on the order of 15 miles.

Looking East.

Looking North.

Looking South.

Looking West.

Ground and Sky Thermal Observations for NearSys Station, 22 December 2017

According to readings from the Seek Reveal, the ground temperature was 13 degrees F. Below are two images of the sky recorded at 4:30 PM MST and 5:15 PM MST. Snowfall began shortly before the second image was recorded.

At 4:30 PM, the stratus clouds over NearSys Station were 9 degrees colder than the ground. Assuming a dry adiobatic lapse rate of 5.4 degrees per thousand feet, the clouds were 1,600 feet above NearSys Station.

Forty-five minutes later, the clouds were 5 degrees warmer. Therefore, the cloud height deceased to 700 feet above NearSys Station. That's a decrease of 900 feet in 45 minutes or 20 feet per minute. Is it normal for clouds to decrease their height before precipitation begins? More testing is called for.

All Sky Photometer Data for NearSys Station, 22 December 2017

It remained overcast all day long at NearSys Station. Then finally around 5:15 PM MST it started to snow lightly. Below is the chart of the all sky photometry data.

The sky became too dark to any effects of the snowfall appropriately 10 minutes before the snow began falling.

Visibility for NearSys Station, 21 December 2017

Finally, the fog and overcast has cleared out. Images from the UAVSonde indicate the visibility at NearSys Station is at least 50 miles.

Looking East

Looking North

Looking South

Looking West

Sky and Ground Thermal Observation for NearSys, 19 December 2017

It's overcast at NearSys Station and the prediction is for rain late tonight and snow in the mountains (which have a dusting right now).  According to the Seek Reveal, the ground temperature is 13 *F And the cloud temperature is 2 *F.

Assuming a dry adiabatic lapse rate of 5.4 degrees per thousand feet, the cloud base is at an altitude of 2,000 feet.

All Sky Photometer Data for NearSys Station, 17 December 2017

Photometer data was collected starting at 6:55 AM MST. Nearsys Station was overcast most of the day.

Ground and Sky Thermal Observation for NearSys Station, 17 December 2017

The coldest ground temperature was 13 *F and the overcast sky had a temperature of 8 *F. With a difference of 5 degrees and a dry adiabatic lapse rate of 5.4 degrees per thousand feet, the cloud base had an altitude of 900 feet.

A uniformly gray sky.

Visibility for NearSys Station, 17 December 2017

The UAVSonde flight indicates that the visibility from NearSys Station is at least 50 miles.

Looking East.

Looking North.

Looking South.

Looking West.

Thermal versus Visible Imaging, part 2

This time I wanted wanted to repeat the experiment but with clear plastic. The plastic in this experiment is acrylic plastic, which is transparent to visible light.

I'm blocking half of my face with transparent acrylic plastic. Since this was taken in visible light, you can see both halves of my face.

The same image, but now taken in long wave infrared.

Thermal versus Visible Imaging

I recently read an article about the ability of thermal imagers to see what our eyes cannot see. It looked so interesting that I decided to try the experiment myself. Here is what I came up with.

Me in visible light.

Me in long wave infrared.

Now you can't see me in visible light because I'm hiding behind a black plastic trash bag (okay, maybe you can tell I'm behind the bag because of the lighting behind me).

But a black plastic trash bag is not good enough to hide me in long wave infrared.

I've learned that some materials will not hide you as you expect in long-wave infrared.

Visibility for NearSys Station, 12 December 2017

A UAVSonde flight at 4:30 PM indicates visibility at NearSys Station is 15 miles.

Looking North

Looking South

Looking West

Ground and Sky Thermal Observation for NearSys Station, 12 December 2017

It's foggy and overcast at NearSys Station today. The ground temperature at 4:30 PM MST was 7 *F and the sky temperature 2 *F. Assuming a dry adiabatic lapse rate of 5.4 degrees per thousand feet, the cloud base is 900 feet AGL.

It's definitely higher than 400 feet since the UAVSonde was visible on station.

All Sky Photometer for NearSys Station, 11 December 2017

Data was collected this morning, an overcast and slightly foggy day. The western Treasure Valley is currently under a temperature inversion.

Umm, it must be severely overcast.

Sky and Ground Thermal Data for NearSys Station, 9 December 2017

The coldest ground temperature is 11 *F And the overhead stratus clouds have a temperature of 2 *F. Assuming a dry adiabatic lapse rate of 5.4 *F per 1,000 feet, the cloud base is 1,700 feet AGL.

Visibility at NearSys Station, 9 December 2017

It's a overcast day at NearSys Station and slightly foggy. The UAVSonde flight indicates that the visibility from NearSys Station is 30 miles.

Looking East

Looking North

Looking South

Looking West

Ground and Sky Thermal Observation for NearSys Station, 3 December 2017

Observations at 5:30 PM MST indicated the ground had a temperature of 18 *F and the clouds had a temperature of 0 *F. Assuming a dry adiabatic lapse rate of 5.4 *F per 1,000 feet predicts the broken stratus has a base height of 3,300 feet.

Thermal image of the broken stratus over NearSys Station.

The appearance of the broken stratus over NearSys Station.

All Sky Photometer for NearSys Station, 2 December 2017

Photometer data was collected in a foggy and cloudy data. The clouds thinned, but the sky did not clear up at 1:30 PM MST.

UAVSonde for NearSys Station, 2 December 2017

UAVSONDE data was collected at 5:20 PM MST, shortly before it got dark. Here are the data.

Altitude: 2,266 feet
Temperature: 57 *F
Relative Humidity: N/A
Pressure: 934.1 mb

Altitude: 2,634 feet
Temperature: 64 *F
Relative Humidity: N/A
Pressure: 912.7 mb

I think it's pretty obvious this weather station is getting old. I plan to either make a new one or purchase a new one. A suitable replacement weather station must have a wireless remote with a range of 400 feet, at a minimum.

Visibility for NearSys Station, 2 December 2017

The UAVSonde recorded the following images from 400 feet AGL. As you can see, it was a foggy morning at 9:00 AM MST. Fortunately, the UAVSonde remained visible from the ground while recording images.

The visibility is not the same in each direction, it appears greatest towards the east at four miles.

Looking east.

Looking north

Looking south.

Looking West.

November Weather Data for NearSys Station

The temperature chart shows we're definitely in a cooling trend since this summer. However, NearSys Station did experience some unexpected warming in November as we experienced a halt in the cooling trend during the middle of the month.

There was gap in recording data during the Thanksgiving Holiday.

November was not a dry month, but NearSys Station only experienced four rain storms.

No snow yet. Very few rain days, but two of them produced ab half inch of rain.