It
all started when I attended a professor’s lecture about the big
ecosystems (biomes) on Earth: tundra, tropical rainforests, taiga,
savanna, forests of temperate zone, deserts, mediterranean
vegetation, and others. It was pointed out how temperature
and humidity
are crucial factors for the development of these biomes. As for the
factor of temperature, various regions of the earth receive different
amounts of the sun’s energy around the year. Even at the same
region there are seasonal variations of sun’s energy distribution.
During the summer the sun is higher in the sky (sun rays fall more
vertically) compared to the winter. In the northern hemisphere sun
rises from south-east and north-east during winter and summer
correspondingly. And sets to the south-west and north-west
respectively. In the northern hemisphere (latitudes > 23.5o)
the sun’s trajectory over the sky has south orientation. In the
southern hemisphere (latitudes > 23.5o)
the sun’s trajectory over the sky has north orientation. At
latitudes close to the equator (< 23.5o
north or south) the sun’s trajectory over the sky has north
orientation during some days or months and south orientation during
the rest (days or months) of the year. Day length is longer during
the summer season and shorter during the winter season. As we
approach the poles of the earth, day length has greater variations.
For example, at regions on the equator the sun is 12 hours above the
horizon, every day, throughout the year. Near the North (or South)
Pole, for several months the sun does not set (it is above the
horizon) and again for several months over the year the sun is below
the horizon!
Since then I have made progress. First I found a way to calculate the day length with the help of geometry - trigonometry. Later on I managed to (somehow) understand useful information I traced on the internet. And now (after a long time) I created an excel worksheet that gives day length and the sun`s trajectory over the sky.
The following application (Microsoft Office Excel worksheet) can be useful to:
-
Architects, engineers and other professions.
-
Researchers.
-
Travelers, school teachers, students, etc.
The
results of calculations are very close to the “true” results for
most of the places of the world. However accuracy is expected to be
less at regions far north or far south of the equator (latitudes over
70o
north or south). You can compare the results with other internet
sites (more official).
I
think the biggest advantage of this application is that it offers
results written on a single worksheet. This data can be easily copied
and used in different applications. For practical reasons, the sun’s
trajectory over the sky is given with intervals of 15 minutes.
The
file is a Microsoft Office Εxcel
worksheet. Ιt’s capacity is
less than 1Mb and it is called “Sun_trajectory_worksheet_V3.xlsx”.
The images below show the excel worksheet and how it looks like:
Image 1. Entering the information data.
Image 2. Results (day length and sun trajectory over the sky)