DocG:

"the fact that there was a layer of frost AND no prints were found in it by the officer IS evidence.It DOES have a bearing on the question of whether there could have been an intruder. "

It certainly is evidence. It's pretty strong evidence that the crime was committed before it formed on the ground and sidewalks if there was an intruder. The same could be said for the snow.

I have been studying the weather data in an effort to determine when the trace of snow/dusting and the frost occured. Here's what I know:

Sunrise/Sunset:
25th. 7:19am/4:41pm
26th. 7:20am/4:41pm

Anbient air Temperature
degrees farenheit, Max./Min./Precip.(snow)/snow accumulation
25th. 54 24 0 T
26th. 51 6 T 0 (Frost point = 11)
Temperature measurements are typically taken at a point 4-5 feet above the ground
Ground temperatures may vary from this by as much as 2 degrees

25th. Relative Humidity: Max = 86%/min = 24%

26th. Relative Humidity: Max = 87%/min = 37%

Using a psychrometric chart (a graphing device that shows the relationships among the various properties of air)
and the above data taken from the National Weather records for Boulder, for the 25th. and 26th. of December,
we can determine the wet bulb temperatures for these days, at least at these times. This tells us the point
at which moisture in the air condenses out as snow or frost.

For the 26th. then, the "dusting" of snow occured when the temperature reached 26 degrees, and continued until the
moisture content of the air fell below the dew point saturation level. Snow, rather than frost is recorded by the
NWS station. For snow to fall, the atmospheric air temperature must be consistently or uniformly below freezing
from the point of crystal formation to the ground.

About Frost:
http://www.awis.com/Misc/Fact_Sheets.htm#UsingDew

"As the air temperature cools on a winter night and approaches the dew point, the moisture in the air will condense out of the air and on to solid objects. The surface temperature of an object must be freezing in order for frost to form. Objects that radiate energy more efficiently tend to frost up first. Thin objects (leaves, small branches, shoots, etc.) frost quicker than thick objects. The ground, particularly when moist, does a relatively good job of holding heat, so frost damage tends to occur at the top of vegetation.

Frost can form when dew point temperatures and air temperatures are in the upper 30s. Patchy and scattered frost can occur in areas that typically run cold, low areas where cold air accumulates, the lee side of wind blocks, etc. In addition, dew point and temperature are measured at the standard height of five feet. It can be colder at ground level.

Prime dew point temperatures for widespread frost formation are in the upper 20s to lower 30s. When this occurs with freezing air temperatures, everything is in place for potentially heavy frost formation.

Frost formation is less likely with dew point temperatures below the mid 20s. There just isn't enough moisture in the air for significant frost formation, even if temperatures are below freezing.

The length of time conditions are favorable for frost formation determines the intensity of frost. The more time the dew point and air temperature hover around or below 30 degrees, the heavier the frost.

Dew point is not the entire story. Other factors also affect frost formation. Wind speeds above 5 MPH slow the radiational cooling of objects, inhibiting frost formation. Cloud cover reduces the effectiveness of radiational cooling. The thicker the cloud cover, the slower the cooling. Soils containing abundant water increase the risk for frost formation by putting more water into the equation, particularly in cases where the dew point temperature is in the mid 20s to mid 30s range. This may counteract the fact that wet soils retain heat better."

One point I wish to make is this: What Officer R saw at 6:15 am the morning of the 26th. as he walked the perimeter of the Ramsey house was the light "dusting of snow", or trace, which he characterised as "frost". You can have frost then snow but not the other way around. When the sun came up at 7:20 the dusting/"frost" was melted_Gone by 8:30ish when the photographers came.

There is no hour by hour data availiable for Boulder. What we may do is approximate the time that the temperature hit 26 degrees. That will give us an idea of when the crime was completed, if by an intruder.