Behavioural Thermoregulation in the Freeze-Tolerant Arctic Caterpillar, Gynaephora Groenlandica

1988 ◽  
Vol 138 (1) ◽  
pp. 181-193 ◽  
Author(s):  
OLGA KUKAL ◽  
BERND HEINRICH ◽  
JOHN G. DUMAN
Keyword(s):  
Solar Radiation ◽  
Growth And Development ◽  
High Arctic ◽  
The Sun ◽  
Metabolic Rates ◽  
Behavioural Thermoregulation ◽  
Body Temperatures ◽  
Feeding Site ◽  
Freeze Tolerant ◽  
Gynaephora Groenlandica

Larvae of the high arctic caterpillar, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae) spent most (60 %) of their time orienting towards the sun (i.e. basking) and only 20% feeding, primarily near midday. Larvae usually basked after feeding, then either fed again or moved to a new feeding site. Basking larvae reached their highest body temperatures (Tb) of ≊30°C (≊20°C in excess of the ambient temperature) when surrounded by snow on a calm day in the midday sun. Setae significantly decreased larval cooling rates. Maximal metabolic rates were attained in basking larvae, but at body temperatures below 10°C oxygen uptake was greatly reduced. Our studies indicate that G. groenlandica larvae are behaviourally adapted to utilize available solar radiation for growth and development.

Behavioural thermoregulation in wintering black ducks: roosting and resting

1984 ◽  
Vol 62 (7) ◽  
pp. 1223-1226 ◽  
Author(s):  
Lynn M. Brodsky ◽  
Patrick J. Weatherhead
Keyword(s):  
Volume Ratio ◽  
Cold Weather ◽  
Energy Costs ◽  
The Sun ◽  
Behavioural Thermoregulation ◽  
Feeding Site ◽  
Convective Heat Loss ◽  
Increase Food Intake ◽  
Consequent Reduction ◽  
Foraging Time

Black ducks (Anas rubripes) wintering near Ottawa, Canada, used a variety of behaviours to reduce their energy costs. The roost site that they occupied provided greater protection from wind than the feeding site, with the consequent reduction in forced convective heat loss. Time spent at the feeding site (i.e., away from the roost) varied with temperature such that ducks maximized their time at the roost on the coldest days. This relationship was facilitated by the ducks' food supply (cracked corn replenished daily), which precluded extending foraging time to increase food intake in cold weather. At the roost ducks huddled in colder weather and adopted postures that reduced both the nonfeathered area exposed to the air and also the surface to volume ratio. The ducks preferentially faced toward the sun and into the wind, but when these were in opposite directions they faced the sun only when wind speed was low.

Evolution of Comets into Asteroids?

1971 ◽  
Vol 12 ◽  
pp. 413-421 ◽  
Author(s):  
B.G. Marsden
Keyword(s):  
Solar Radiation ◽  
Solar Nebula ◽  
Oort Cloud ◽  
Original Version ◽  
Terrestrial Planets ◽  
Minor Planets ◽  
The Sun ◽  
Physical Difference ◽  
Short Period ◽  
The One

There has long been speculation as to whether comets evolve into asteroidal objects. On the one hand, in the original version of the Oort (1950) hypothesis, the cometary cloud was supposed to have formed initially from the same material that produced the minor planets; and an obvious corollary was that the main physical difference between comets and minor planets would be that the latter had long since lost their icy surfaces on account of persistent exposure to strong solar radiation (Öpik, 1963). However, following a suggestion by Kuiper (1951), it is now quite widely believed that, whereas the terrestrial planets and minor planets condensed in the inner regions of the primordial solar nebula, icy objects such as comets would have formed more naturally in the outer parts, perhaps even beyond the orbit of Neptune (Cameron, 1962; Whipple, 1964a). Furthermore, recent studies of the evolution of the short-period comets indicate that it is not possible to produce the observed orbital distribution from the Oort cloud, even when multiple encounters with Jupiter are considered (Havnes, 1970). We must now seriously entertain the possibility that most of the short-period orbits evolved directly from low-inclination, low-eccentricity orbits with perihelia initially in the region between, say, the orbits of Saturn and Neptune, and that these comets have never been in the traditional cloud at great distances from the Sun.

3. Note on Solar Radiation

1888 ◽  
Vol 14 ◽  
pp. 118-121
Author(s):  
John Aitken
Keyword(s):  
Solar Radiation ◽  
The Sun ◽  
Geological History ◽  
Conservation Of Energy ◽  
Vast Amount ◽  
Chemical Theory ◽  
Energy Theory ◽  
The Many ◽  
Different Sources

In the many theories that have been advanced to explain the comparative constancy of solar radiation in long past ages as evidenced by geological history, it has been generally assumed that the temperature of the sun has not varied much, and to account for its not falling in temperature a number of theories have been advanced, all suggesting different sources from which it may have received the energy which it radiates as heat. Since the chemical theory was shown to be insufficient to account for the vast amount of heat radiated, other theories, such as the meteoric theory and the conservation of energy theory, have been advanced.

scholarly journals ON THE EFFECTS OF SOLAR RADIATION PRESSURE ON THE DEVIATION OF ASTEROIDS

2021 ◽  
Vol 57 (2) ◽  
pp. 279-295
Author(s):  
L. O. Marchi ◽  
D. M. Sanchez ◽  
F. C. F. Venditti ◽  
A. F. B. A. Prado ◽  
A. K. Misra
Keyword(s):  
Solar Radiation ◽  
Radiation Pressure ◽  
Scientific Research ◽  
Orbital Plane ◽  
Solar Radiation Pressure ◽  
The Sun ◽  
Mass Ratio ◽  
High Area ◽  
Planetary Defense

In this work, we study the effects of solar radiation pressure (SRP) on the problem of changing the orbit of an asteroid to support planetary defense, scientific research, or exploitation of materials. This alternative considers a tethered reflective balloon (or a set of reflective balloons) attached to the asteroid, with a high area-to-mass ratio, to use the SRP to deflect a potentially hazardous asteroid (PHA) or to approximate the target asteroid to Earth. The tether is assumed to be inextensible and massless, and the motion is described only in the orbital plane of the asteroid around the Sun. The model is then used to study the effects that the tether length, the reflectivity coefficient, and the area-to-mass ratio have on the deviation of the trajectory of the asteroid.

scholarly journals Minimizing the Cosine Loss in a Solar Tower Power Plant by a Change in the Heliostat Position and Number

2020 ◽  
Vol 9 (3) ◽  
pp. 2302-2304
Keyword(s):  
Solar Radiation ◽  
Tracking System ◽  
Working Fluid ◽  
The Sun ◽  
Incident Solar Radiation ◽  
Concentrated Solar Energy ◽  
Central Receiver ◽  
Receiver System ◽  
Concentrated Solar Radiation ◽  
Solar Rays

Concentrating Solar Power (CSP) focuses sunlight in order to use the heat energy of the sun. In a central receiver system configuration, many mirrors (heliostats) individually track the sun and reflect the concentrated solar energy onto a receiver on top of a tower. The receiver contains the working fluid which is heated by the concentrated solar radiation. The useful energy that absorbed by the water flows through the receiver in solar tower plant depending on the angle between the solar rays and the position of heliostat in the region of work. Heliostat will reflect the incident solar radiation in the direction of the receiver founded in the top of the tower, in order to get a maximum incident solar radiation on the heliostat reflection area. Because of the cosine factor loss effect due to the sun position is variable along the day from sunrise to sunset, which must be in a minimum value, therefore an automated tracking system with dual axes as a control system with sensors had been built and used to stay the sunrays incident on the receiver, and enable the heliostat to flow the sun where it was

scholarly journals Solar radiation transposition models applied to a plane tracking the sun

Solar Energy ◽  
1988 ◽  
Vol 41 (4) ◽  
pp. 371-377 ◽  
Author(s):  
P. Ineichen ◽  
A. Zelenka ◽  
O. Guisan ◽  
A. Razafindraibe
Keyword(s):  
Solar Radiation ◽  
The Sun
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