Climate Space Model

Climate Space Model VISTA USERS READ THIS TO RUN THE PROGRAMS

Model Structure:

The heat transfer coefficient is in cal/h°C. This coefficient describes how quickly the animal absorbs heat. Do Not Exceed 60 cal/h°C or the program will lock up (hit the refresh button if that happens)
The air temperature (in °C) affects the rate at which your animal will absorb heat.
Solar radiation is in cal/hr and ranges from 0 to about 3000 as reasonable units.
The equilibrium body temperature (shown in the lower left graph) is described as where be_i is the calculated body temperature, q_i is the solar radiation in cal/hr, h is the heat transfer coefficient (in cal/h°C), and a is the ambient air temperature (in °C).
The upper lethal and lower lethal body temperatures are in °C.
The solar radiation for the day and night are in °C.
The upper limit climate4 space is described by while the lower limit climate space is described as .
TRh are potential air temperatures at an exposed rock while SRh is the potential solar radiation for the rock. TBh and SBh are the corresponding values for a protected bush.
The values entered in the upper right table are reasonable values for the air temperature near an exposed rock (TR) and the solar radiation near an exposed rock (SR). These are shown for the hours 00:00 through 21:00. Simlar data are presented for a bush. TB is the air temperature near the bush while SB is the solar radiation.
After pressing the "Check it out" button, The area between the straight lines is the climate space for an upper safe limit of 36 oC and a lower safe limit of 24°C. Convective heat transfer coefficient is assumed to be 50 cal/(h°C). The loops illustrate possible combinations of air temperature and solar radiation for two types of habitats: a protected bush (green) and an exposed rock (brown).

If you press the "Check it out!" button with the default values, you will end up with the following graph:

climate.gif (8811 bytes)

This graph shows the upper lethal limit (the straight line in red) and lower lethal limit (straight line in blue) as well as the temperature near a bush (green) and a rock (brown) over the 24-hour period (the time goes counter-clockwise on the graph; arrows). From the graph ypou can see that the temperature is above the upper limit at 12:00 for both the bush and the rock. Therefore we would expect our model animal to hide at this time (perhaps in a burrow). Between 06:00 and 18:00 the animal can forage at the bush, but not the rock (since the rock is above the upper lethal limit). At 00:00 the animal cannot survive near the bush, but the rock provides sufficient heat.

Thus, based on the climate space data we would expect the following behavior:

Time	Expected Behavior	Explanation
00:00	Hide in burrow	Rock and bush temperatures are under lower lethal limit.
03:00	Forage at rock	Rock temperture is acceptable, bush still too low.
06:00	Forage at bush	Rock temperature is now too high. Bush is now optimum temperature
09:00	Forage at bush	Bush temperature is very close to upper lethal limit, but appears to be in range.
12:00	Hide in burrow	Both rock and bush are above upper lethal limit
15:00	Forage at bush	Bush is at optimal temperature. Rock is too hot.
18:00	Forage at bush or rock	Probably mostly rock since that's in the center of optimal temperature and bush temperature is near the lower lethal limit.
21:00	Hide in burrow	Both rock and bush are below lower lethal limit.

Explore the effects of changing the variables (one at a time) to understand how this animal should behave under various environmental conditions. Press the Refresh button on your browser to return to the original values.