winter ventilation and pocket IR thermometer

Last year as an impulse buy, I purchased an inexpensive RadioShack Waterproof Pocket IR Thermometer.  This budget gadget has a limited range, so get close to your target when taking a temperature reading.  At dawn I record the top vent and concrete paver temperature.  The paver sits on top of the hive and acts as a surrogate for smoothed outdoor air temperature.  The top vent temperature acts as surrogate for bee respiration temperature.  Imagine this - on cool mornings, the bees are tucked inside the hive, cold air flows into the entrance and screened bottom while warm moist bee respiration exits the top vent - sometimes I discover the warm moist air condensed to the outside of the hive cover - see photo.  

What is the relationship between outdoor air and bee respiration temperature?  During a cool morning, the respiration temperature is greater than the air temperature.  In other words, all graph points (and trend lines) lie above the y= x line.  For example, a dead hive plots on the y= x line.  Bee respiration temperature decreases with decreasing outdoor temperature - this is consistent with air exiting the top vent as a mixture of fresh air and bee respiration.  In other words, the warm bee respiration is diluted by cooler fresh air.

How do the hives differ?  Three hives (Kent, Buda and Pest) are located in a row, but each has a unique amount of shade and access to morning sunshine.

• Pest's third order polynomial trend line respiration temperature is warmer than the other hive trend lines. Probably Pest has the largest bee population. Pest is a 2011 swarm, captured with the help of Cassandra and John. Pest is a powerful force of nature - what Cassandra refers to type A behavior.
• Kent's trend line respiration is less warm than the Pest trend, yet Kent usually flys more vigorously than the other hives. FYI, Kent receives more morning sunshine than the other hives. My range of temperature measurements (Nov 18th to Dec 3rd) contains many stretches where the mid-day outdoor temperature is too low for foraging. Perhaps Kent's interesting sigmoid trend line represents 1) winter clustering in the flat lower left region, 2) typical non-clustered state in the flat upper right region and 3) a sloped line which represents a continuum of changes connecting these end-points.
• Buda's trend line respiration is cooler than the other two hives. Buda is a 2012 spring split. Probably Buda has the smallest bee population compared to the other over-wintered hives.

warm bee respiration and non-invasive winter measurements

I am using an inexpensive RadioShack Waterproof Pocket IR Thermometer to measure temperature differences between cool outdoor air and warm bee respiration.  Winter temperatures arrived and this makes these contrasting temperature measurements possible.  At dawn I record the top vent and concrete paver temperature.  The concrete paver sits on top of the hive and acts as a surrogate for smoothed outdoor air temperature. These 2014 measurements are a follow up from a previous post two years ago, winter ventilation and pocket IR thermometer.

I have three bee hives (Kent, Buda and Pest) and mid-day flight activity at the Kent hive is consistently greater than the other two hives.    

If hive visits do not permit mid-day flight observation, then this non-invasive method provides some assurance that:

• The hive is still alive provided that the graph points are above the green x= y line.
• Greater contrast with outdoor temperatures correlate with increased mid-day flight activity.  The Kent hive trend line is further from the green x= y line, while less flight active hives have a trend line closer to green x= y line.

honey consumption and late winter brood rearing

My 8-frame hive is wrapped in a hive cozy. On warm afternoons in December and January, bees flew vigorously and performed orientation flight. These 2021-2022 measurements show that bees are most likely consuming their honey stores and raising late winter brood.  

• Temperature measurements are taken at dawn at the top vent using an inexpensive RadioShack Waterproof Pocket IR Thermometer. The orange trend line is most likely an increase in total bee metabolism/respiration (bees covering late winter brood). Peak temperature top vent measurement of 78°F (25.6ºC) is not the expected 89.6-96.8°F (32-36ºC) brood nest temperature, so why? Cold air flows into the hive entrance and screened bottom board and mixes with warm moist bee respiration and exits the top vent - usually I discover the warm moist air condensed to the outside of the hive cover.
  
• Less frequently, I weigh the hive using an inexpensive luggage scale. The green trend line is most likely winter consumption of honey stores. I would prefer to connect densely sampled weight measurements (points) with a spline instead of the polynomial trend line.  However, extra hive weight measurements are not possible with my travel schedule. 
• Also shown are HoneyBeeNet 2012 hive weight measurements from Cowetta GA (40 miles from Atlanta). HoneyBeeNet is a NASA hive and climate citizen science project. The zoom into these end of year weight measurements show a similar sharp drop in hive weight.