We think of the core as an insignificant player in our worlds climate and continually flows energy up towards the surface and out of the ground and the Earth as just a heat sink for energy during the summer months. What has not been defined and explained is the complete system, and it has measurable and explainable events with direct effects.
Beginning of the Conduction Cycle
Autumn begins at different times depending upon the location, but they all follow the same pattern. Using the data from the Minneapolis International Airport, the first day the temperature dropped to 30F or less was plotted and averaged out since 1900. This temperature creates a killing frost event that has a great impact upon the vegetation, insects and a reverberating effect upon all life. In Minneapolis the average date that this occurs is on day 291, which is October 18th, October 17th on leap years. This also coincides with the average for the peak season for fall colors. Within a few weeks all the vegetation has dropped shutting down the transpiration cycle and the Earth begins to conserve energy for the cold winter months ahead. Generated from the reduction in solar energy due to the axial tilt, conduction flow begins and the Earth begins to cool and the atmosphere begins to have a greater influence on the weather than the daytime sun. Only locations where evening temperatures drop below 50F on a continual basis are subject to this event, and areas that average temperatures above these temperatures maintain their vegetation, like the Gulf Coast or Pacific Southwest.
Using the 160cm depth below ground, the date the conduction cycle begins was plotted, along with the first 30F low. This demonstrates that temperatures of 30F are achieved, on average, within 5 days after conduction begins at 160cm. Underground data for complete years was only available from 2000 to 2014 for analysis.
Autumn brings out all the vibrant colors of our world, and we all enjoy this period of time, but there is far more going on with this event. It's a time when life goes underground and the earth attempts to maintain as much warmth as possible in preparation for the cold winter ahead. The transpiration cycle ends with this event and literally falls to the ground. During the summer months, when the surface is warmer than the subterranean region, the only means of release for the accumulating heat is through convection, and the transpiration cycle accelerates this process through water vapor. When the leaves fall, the earth is now exposed to the incoming solar energy further adding energy upon the surface. When the snow comes this clutter, known as thatch, creates an air pocket between the surface and the snow similar to the thermopane windows we use further insulating the subterranean.
Transpiration Cycle, Spring Charging
In the spring, and before the bloom, the thatch maintains a cool damp environment below and protects it from impact splash due to the spring rains and promotes infiltration. This environment then accelerates decay as the temperatures warm releasing CO2 and fueling the spring bloom. When the lakes are clear of ice and the frost is out of the ground the thermal switch activates and heat begins to build from the top down. This is due to the law that energy in the form of heat can ONLY flow from hot to cold, so when the surface becomes warmer than the subterranean layers below, this occurs. In Minnesota, on average, this occurs 5 feet beneath the surface by the end of April and coincides with the spring bloom. With the reversal in energy flow forcing the rising energy to build the only way for heat to be released is through the water. At night, the vegetation alters and releases water vapor in the form of transpiration exhausting the daily heat. In this process, as a whole forest or prairie, the mass acts as a radiator for our planet allowing this dormant heat to be released and shelters the surface from the incoming solar radiance. Although the earth uses water throughout the year to discharge heat, the transpiration cycle during the summers massively accelerates this process.
When land is altered for farm production and urban development there is a yearly increase in heat over time, and the length of the seasons alters. In the spring they act like preheating an oven, and the heat is maintained longer extending the seasonal length. Although this energy reversal occurs earlier in the spring and in the fall as well, when soils temperatures at Swan Lake were reviewed the temperature at 150cm was .4C warmer under raw dirt even though it had been exhausting weeks prior to sod covered soils. There is also a change in precipitation and when conduction is shut down, water is vital for cooling.
When land is altered for farm production and urban development there is a yearly increase in heat over time, and the length of the seasons alters. In the spring they act like preheating an oven, and the heat is maintained longer extending the seasonal length. Although this energy reversal occurs earlier in the spring and in the fall as well, when soils temperatures at Swan Lake were reviewed the temperature at 150cm was .4C warmer under raw dirt even though it had been exhausting weeks prior to sod covered soils. There is also a change in precipitation and when conduction is shut down, water is vital for cooling.
In this graph we can see the day that conduction ends at 160cm, just over five feet beneath the surface. Altering only slightly from day 120 (April 30) to day 118. The force generating this event is the planets axial tilt altering the day light hours. Due to the axial tilt the maximum registered alterations beneath the soils have only increased by a maximum of .05C from one year to the next, but also only reduce by no more than .06C per year on average through 2014.