METABOLIC ALLOMETRY... 'm' Use this
somewhat specialized utility to make estimates of an animal's resting metabolism,
based on its size and taxonomic affiliation. The metabolism calculator has many potential uses; for example, you might want to use it as a 'reality check' if you think your own metabolic data are unexpectedly high or low.
The initial popup menu contains some very generalized equations, and also allows you to switch
to submenus for specific taxa (arthropods,
fish, birds, mammals, etc.). For most taxa, several different equations
are available (from different literature sources, which are described in
the 'help' field to the right). You can also pick the desired output
units. The energy equivalence of metabolism (joules per ml of oxygen
is set at 20.1 joules/ml (this varies -- but not by very much -- with different metabolic fuels). The mass coefficient in the allometric equation
('a' value) is adjusted to reflect whatever output unit is in use.
Results can be stored for later use.
Metabolism for all taxa are calculated from power functions:
metabolism = a Mb
(where a is the mass coefficient, M is mass, and b is the mass exponent)
This example shows an estimate of the resting metabolic rate (RMR) of
a 37.3 g bird, in units of ml O2/min.
The equation was derived from a paper published by Andrew Mckechnie and
Blair Wolf (Click here for a list of the references from which allometric equations were obtained.).
Note that the mass coefficient ('a' value)
and mass exponent are shown and can be edited, and that mass can be in either grams or kilograms. Also, it is possible
to make corrections for the effect of body temperature by making the appropriate
adjustments to the value of Tb and
Q10 (in this example, the 'base' Tb,
from which the equation was derived, is equal to the current Tb
so no temperature correction occurs). After changing values in the
edit fields, click the 'Compute' button to display the new results.
SUNRISE, SUNSET... This utility uses the well-known ‘Sunrise equation’ to compute the approximate times of sunrise and sunset from date (month, day, year) and location (degrees latitude and longitude). You need to select North or South latitude, and East or West longitude relative to the Prime Meridian.
NOTE: The program expects latitude and longitude in fractional degrees, not degrees and minutes. Thus 27° 30’ north should be entered as ’27.5’ (i.e., halfway between 27° N and 28° N).
Sun time estimates are approximate for several reasons:
• Sunrise and sunset times are based on local solar noon (i.e., when the sun is at its zenith (highest above the horizon) from the perspective of the observer’s position. This is likely to be slightly different from local time. As defined by people, time zones are arbitrary, and since they are roughly 15 ° of longitude wide and often do not run strictly north and south, sunrise and sunset times can vary by an hour or more with a single time zone.
NOTE: The U.S. Naval Observatory hosts a web page (USNO Sun and Moon Data) that permits very accurate calculations of solar and lunar data. It incorporates ‘fixes’ for many of the issues described above, and — if you are connected to the internet — can be accessed with the ‘Naval Observatory Website’ button.
• The calculator has no allowance for elevation above sea level (which makes rise times earlier and set times later, if the horizon is at sea level). It also has no allowance for local topography — for example, if the observer is in a deep valley, the visual horizon is elevated above the ‘real’ horizon, and rise times will be later and set times will be earlier than shown here.
• The precise times of sunrise and sunset are of concern to astronomers and the like, but for most purposes they are rather ‘fuzzy’ due to the angular diameter of the solar disc (about 32 minutes of arc or 0.53 degrees), atmospheric refraction, etc.
• The 'Get Latitude and Longitude From World Map' button opens a window with a world map (d'oh!) in Mercator projection. Move the cursor to the desired location and hit either the spacebar or return keys to select that position; as you move the cursor the latitude and longitude boxes at upper left update continuously. If you want to select a position on a higher-resolution 'regional' map, click the Zoom in X5 button, a rectangular cursor appears; move it until it encloses your area of interest and hit either the spacebar or return keys to enlarge that region. Then use the cursor and keys to select a position as described above.
Location data are accurate only to 0.33 degree of longitude and 0.25 degree of latitude on the world map and 0.11 degrees of longitude and latitude on the regional maps, but that should be accurate enough for most sunrise-sunset calculations.
As geographic references, the maps show the equator (yellow), the Prime or Greenwich Meridian (zero degrees of longitude), the Arctic and Antarctic Circles (~ 66.5 degrees N and S), and the Tropics of Cancer and Capricorn (~ 23.3 degrees N and S). Only a few of these will be visible on the enlarged regional maps.
Of course, if you want higher-resolution position data (and you are connected to the Internet), use Google Earth.
• The 'Annual Plot' button will compute and display an entire year's day length cycle, based on latitude-longitude position. The 'Print Data to Spreadsheet' button makes a tab-delineated .xls spreadsheet containing the annual cycle (date, sunrise time, sunset time, and day length). This example shows a Polar-region cycle, with complete darkness in winter and 24-hour sunlight in summer:
UNIT CONVERSIONS... This calculator will convert many commonly-used units into other units. The conversions are arranged by type, selected with the radio buttons on the right of the window. This utility will also estimate certain biophysical and meteorological data. In the example below, solar radiation intensity is estimated as a function of how far the sun is above the horizon.