Evaluating Sunshine

nraged

Well-Known Member
Sunshine is important to outdoor growers, it can make the difference between small scrawny buds and big chunky ones. Its important to know if a potential plot will provide as much light as possible.

In the northern Hemisphere, the shortest day of the year usually takes place on December 21(june 21 in southern hemisphere), this is the lowest in the sky the sun will set for the year, this is called the Winter solstice.
At the oposite time of the year you have the Summer solstice, usually on June 21(December 21 in S. Hem), this is the longest day of the year, the sun will be the highest in the sky.
Halfway between we have the Sping equinox(March 20th in N. Hem, Sept 22 in S. Hem) and Autumn equinox(Sept 22 in N. Hem, March 20 in S. Hem). The equinoxes mark the halfway point between the longest and shortest days of the year, the Sping equinox occurs while the day is getting longer heading to summer, the Autumn occurs while day is getting shorter and heading towards winter. These changes in day length are what tells the Cannabis plant when to bloom in relation to the change of seasons.

Links to Wikpedia explaining: The Equinoxes and The Solstices




Your Compass, and how to use it
Compass use is not as difficult as it may seem, and for the purpose of finding simple directions, its fairly easy.

Take a look at these diagrams-



On the compass dial(or benzel) is printed a series of numbers, these are your "Degrees of azimuth", N(orth) is zero, E(ast) is 90, S(outh) is 180, and W(est) is 270. All together there are 360 degrees of azimuth, each degree represents a direction on the compass.

To find a given direction, for instance 240 degrees south-west, turn the dial of the compass until the number 240 lines up with the direction of travel arrow.
Now turn your compass until the red tip of the needle lines up on the orienting arrow, pointing the same direction as it is, your compass is now pointing 240 degrees SW.
Use this same method to find any direction on the dial.

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A basic method to evaluate sunshine potential
Sit where your plants will be growing, take your compass and find east, south, then west, scan the southern sky between east and west. Is it pretty clear? No trees, or hills near by to block light? If 75% of the sky or more is clear, you have a good plot.

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A slightly more advaced way to evaluate sunshine potential
When I evalute a plots sunshine potential, I sit where the plants will be. I take my compass and find due south, this is the middle of the suns arc through the sky. Now I point the compass to my left and find 105 degrees east, then I point the compass to my right and find 255 degrees west. Now I look at the southern sky between those east and west points, hopefully no trees, bushes or nearby hill tops block this view, if they do, they might affect the quality of light hitting the spot. If it looks good, this should be enough light to grow a good crop, more unblocked sky would be even better.

As long as this portion of the sky is clear, it is advantageous to have brush and other vegetation around the plot, this will help keep it unseen from those who may pass by.

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A very advanced way to evaluate sunshine potential
But what if you have a plot with bushes or trees in front of it, and you arent sure wether they are low enough not to block light, Or perhaps you are on a steep hillside, and a tall tree or nearby ridgeline in front of the plot makes you nervous. This is where a Inclinomter and sunchart come in.

Inclinometers
Inclinometers are used to mesure angles in degrees, used with a Sunchart taylor made for your area, you can predict where the sun will sit in the sky at each hour of the day, all year long. Once you learn how to do it, it can make evaluating the sunshine potential for a plot very acurate and reliable, and can help you approve or disprove a plots potential quickly. Also , you will be able to plant in areas with more vegetation surrounding the plot for cover, since you will know exactly where the sun will shine from.

Sunchart
The sunchart shows the path of the sun in blue for each month, red lines representing each hour of the day cross the blue lines. A grid shows compass direction(Azimuth) with lines runing from top to bottom, and lines running from left to right show elevation.


I will give a example from a chart for my area, as seen above.
I want to find where the sun will be at 4PM on Aug 22, following the red time of day line, down to the Aug 22 blue sunpath line I see that the sun will appear in the sky that day and hour at @ 255 degrees west and at @ 30 degrees of elevation.

Making your own sun chart
Here is a link to a sunchart generator>>> University of Oregon SRML Sun path chart program

On the first page you will find a series of steps, fill each one out-

Step 1—Specify location: You can either write in your zip code, or enter your Latitude and

Longitude if you know them.

Step 2—Specify time zone

Step 3—Choose data to be plotted: This will select which half of the year your sun chart

will be for, I usually just make a June through December chart, also choose local standard time.

Step 4 to 6— These settings are best left as is.

Step 7-Create your chart!

Finding a Inclinometer
Inclinometers are commonly found at tool stores and at hiking/mountaineering/camping stores.
The tool store variety is used for mesuring inclines on objects like driveways, roofs and other projects where knowing the angle of a incline may be important. The ones found in hiking stores are usually built into a compass, and are used to find the elevation of objects like mountains, trees, etc.



You can even make your own Inclinometer at home from things you may have on hand, for free!
Link to directions for Homemade Inclinomter>>Making Your Inclinometer
There is also a link at the bottom of the screen that will take you to a page showing how to use your inclinomter for finding the height of objects.

Using your Sunchart, Inclinometer, and Compass together
Lets say I am evaluating a plot, I sit where the plants will grow, taking my compass I find the furthest east the sky is clear, which is 120 degrees east. Now I look at my Sunchart and find that the sun will be at 58 degrees elevation at that Azimuth on June 21(the longest day of the year) and at 12 degrees elevation on October 21(near the end of my grow season).

Now using my inclinometer, I aim it at 120 degrees east with the compass, now I raise or lower the inclinometer until the bottom of the horizen is in its sights, the inclinomter will now display the elevation I sighted at, which is 10 degrees, this means sunlight will reach my plants June through October from this direction.
I continue using these tools to evaluate the southern sky from east to west, until I am sure the sky will be clear to my plants from June through October, If my needs for sunshine are met, this site will pass the test.


 

Angus

Well-Known Member
Nice writeup man. Lots of helpful stuff in one place. I'm sure I'll refer back to it. I believe I'll make an inclinometer for for s&g's...

thanks again

...oh yeah it is a picture of some scales not a tree...
 
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