Daylight Hours Explorer

[Romeu9]

Daylight Hours Explorer

Shows the hours of daylight received during the year for an observer at a given latitude. This is an important factor contributing to the seasons.

UNL Astronomy / ClassAction

/ Coordinates and Motions / Animations

Usage Instructions

Running this animation on your computer...

1. right-click to download daylighthoursexplorer.swf and daylighthoursexplorer.html to the same directory
   
2. open the html file in a browser to run the animation
   

http://astro.unl.edu...rsexplorer.html

To find your latitude use Google Earth or Maps

Take care

[indicando]

Sticky please.

Great catch Romeu9

[Guest dfwi]

Great tool Rom isnt the net wonderful...........Love your work good find

[RIX]

Not sure if it was you or toroa is it? who mentio a iphone app the gives real good information.

How the world is changing...

Take care

ps we do need sticky or a section for stuff like this,may be just a sticky with good reliable links and brief adcice information on idea conditions and light angles..

[kdstanhope]

Sup folks! Isn't technology wonderful! I've used this tool before, it is great to give you an idea of times etc... but if you want to be even more hardcore, in fact it may be overkill, there is a GIS program called GRASS. I put a link to it in a post from a while back.

Its a bit of a run around, but its free. It allows you to create a solar irradiance map. from the manual:

Computes direct (beam), diffuse and reflected solar irradiation raster maps for given day, latitude, surface and atmospheric conditions. Solar parameters (e.g. sunrise, sunset times, declination, extraterrestrial irradiance, daylight length) are saved in the map history file. Alternatively, a local time can be specified to compute solar incidence angle and/or irradiance raster maps. The shadowing effect of the topography is optionally incorporated.

You can download the SRTM terrain models from NASA - it is the lat, long and elevation coordinates for specific points arranged in a grid at intervals ranging from 20metres to 90metres, it covers the whole world, that you plug into GRASS and just like that, you can pick the optimal spot for your outdoor grow!

Sorry if this is way overkill....

[kdstanhope]

Ok, so I got REALLY keen, please excuse my exuberance... Here is a short render of a graphical example of what I was talking about earlier....

The time frame is about 10am - 4pm. Mid-summer, southern hemisphere, LO31.

The green shading indicates sunlight (and diffuse light) striking at an agle < 70 degrees

The darker the shade, the more extreme the angle.

the white light areas indicate areas where sunlight angle is direct ( angle between 80 and 100)

From this you will then go on to calculating the average or total over an entire grow period to find which area is the most efficient...

OK, I can't get the vid to work.... if anyone is interested, heres the link

[indicando]

kds,

I think more then that, just look the sun...it goes east to west..

maybe I'm missing your point

[kdstanhope]

Like I said; hardcore.

It is over kill, but the aspect and gradient of a slope will greatly effect the amount of sunlight a given area receives. Look at the lengths that indoor growers go to to get the perfect crop; artificial enviroment deluxe. Why not throw some of that perfection into the mix when doing an outdoor crop? Plant with alfalfa and clovers, use valley climates to your advantage etc etc... Planning makes life easier later on - its not like you can dig up the plants and move them to a better area later in the season.

[indicando]

on win7 I cannot get GRASS running

[kdstanhope]

Ja, GRASS is a mission. You need GRASS for windows. "WinGRASS-6.4.0-1-Setup.exe"

Once you install it it is a bit of a mission to get it up and running... There is a gui, but the command line interface is where its at! there should be an icon on your desktop called "GRASS 6.4.0 with MSYS"

The software is linux based so the commands are much the same as msdos but closer to bash. Also, the software does not like spaces.... so install it to something like C:GRASSS not C:Program Files(x86). The space confuses it.

Once you open up the MSYS program, you will need to define a mapset (your geographical location), then "START GRASS" then use the yellow window to run your scripts. You will use "r.sun" There is a lot of documentation on the web for it

Look, its a real bitch to do if you going from scratch. But if you're interested indicando (or anyone for that matter), PM me and I'll do a solar irradiation map of your area using the NASA data (and ARC Desktop). Not sure what I can do about orthophoto's, I only have for my country, but I'm sure you could overlay the data onto Google Earth.

PEACE!

[indicando]

We can keep the chat public, so everyone will benefit,

How do I load a HTG map is it any good ? I just found this of my country

can you make an example of usage or r.sun please

[kdstanhope]

Groovy

If you have GRASS all ready to go then check out the usage below. HGT files are fine but we will have to convert them to elevation raster maps, see below.

Firstly you need to make sure that the installation path for GRASS contains no spaces. So for instance I have grass in D:GRASS-64

Open up grass with msys. You will be confronted with a command line vibe and a second window called Welcome to Grass. In this window, you will first need to define the correct data directory, this is quite important. So browse to the folder that you installed grass to and set the data dir as;

C:GRASS-64msyshomeSTANHOPE

the ...msyshome"name" is the important part, as this is where you will place all your working files.

Next, click on the location wizard.

This part is a little tricky. You need to define a projection system. I think that the easiest thing to do would be to go onto your local, provincial or government GIS website and try and find a shape file for something like the distibution of man-holes or something similair, with those files, one of them will be a *.prj file. this is a projection file and you can use this file to tell grass which datum and projection you are using.

It is important that you select a projection and datum that is the same as your height model or everything will go wrong.

You can also enter the details in manually. I reccommend going with either the pseudo-geographic (code:ll) or transverse mercator (code:tmerc). The HGT file is referenced to the WGS84 ellipsoid. AS far as I know, the SRTM elevation models are .hgt files at 90m which means each point of elevation is 90m apart.

Open an explorer window and browse to your msyshome*name* directory and paste your hgt file there. Make sure the filename contains no spaces.

Right, now that all that is set up. you need to click create mapset, give it any name you want, and click start grass.

In the GRASS side of things, there should be three windows open now, Map Display, Layer Manager and sh. go into the yellow sh command line window and type ls or dir.

it should spit out a list of files in the current directory, for instance, mine says:

3122DD12.ORT Cane slopeaspect.tiff FORGRASS SOUTHAFRICA

fieldmaker_script

you will need to make sure that your .hgt file shows up, or you are in the wrong data directory and you should either go back and change your data directory or include the correct path in your r.sun command. It is easier to change the grass data directory...

Now for the magic. Unfortunately, you will need a 32bit float elevation raster map, so we will first have to convert your hgt model into a raster data set, so here is the command you will have to type:

r.in.srtm input="hgt file name" output="any name you want"

Keep your fingers crossed and wait for it to finish.

now type ls again, you should see your newly created raster map in the same directory.

Now we are ready to do r.sun. the complete syntax is:

r.sun [-s] elevin=string aspin=string slopein=string [linkein=string] [lin=float] [albedo=string] [alb=float] [latin=string] [lat=float] [coefbh=string] [coefdh=string] [incidout=string] [beam_rad=string] [insol_time=string] [diff_rad=string] [refl_rad=string] day=integer[step=float] [declin=float] [time=float] [--overwrite]

But you wont have to type all of it in. Just the importand parts.

A good start would be:

r.sun -s elevin="raster_map_name" aspin="raster_map_name" slopein="raster_map_name" lat="your closest_line_of_latitude" day="days_to_calculate_ie:1-365"

Then wait for it to finish. It could be a long time depending on your cpu and the size of the area.

Then use the map display to view your magic!

Other software that does an AMAZING job is ArcDesktop. This is what I use. But it isn't free and it requires a licence and such...

I hope that I have been of some assistance, everyone here is always so helpful and welcoming when it comes to helping others out, I hope my contribution is useful. And really, if you give me your .hgt.zip file I will do a irradience map quich sharp and send it back with a neat layout and a bunch of gps coordinates for the areas of highest kW.m-2.

Peace Everyone!

[kdstanhope]

A script to help with the r.sun adventure, just select all the text below and save it as a *.sh file. to run the script just type ./script_name.sh in the grass console. Remember to create your elevation raster first though!

#!/bin/sh

#elevation map

echo "Enter elevation map:"

read elev

#slope map

echo "Enter slope map:"

read slope

#aspect map

echo "Enter aspect map:"

read aspect

#turbidity (single float value)

#echo "Enter Linke Turbidity: an average value would be 2"

read turbidity

#first day

#echo "Enter first day of calculation:"

read start

#last day

#echo "Enter last day of calculation:"

read end

#start=1

#end=31

i=$start

#generate empty map for global radiation

r.mapcalc "global_1km=0"

#for DAY in {$start..7} ; do

while [ $i -le $end ]

do

DAY_STR=`echo $i | awk '{printf("%.03d", $1)}'`

echo "Processing day $DAY_STR at `date` ..."

r.sun -s elevin=$elev slope=$slope aspect=$aspect day=$i lin=$turbidity step=0.5

beam_rad=rad_beam.$DAY_STR diff_rad=rad_diffuse.$DAY_STR

refl_rad=rad_reflected.$DAY_STR

#calculate global irradiance

r.mapcalc "global_1km=global_1km+rad_beam.$DAY_STR+rad_diffuse.$DAY_STR

+rad_reflected.$DAY_STR"

#remove created raster

g.remove rast=rad_beam.$DAY_STR,rad_diffuse.$DAY_STR,rad_reflected.$DAY_STR

i=`expr $i + 1`

done

#calculate average daily irradiance of given period of time

r.mapcalc "global_1km=global_1km/($end-$start+1)"

[kupobg]

Don't understand crap .... dont need it tho (i think)

[Maffro]

Blinkin heck its like being back at uni !

Good tech for the outdoor grower - especially when choosing a spot to start. check your spot is usually sunny in the morning so the dew gets evaporated - ive found thats a grand problem when it comes to bud mould !

[hexx]

True, they do like lots of Sun.

[metthc]

Thanks a lot. Very useful.

[zcabsa]

really interesting

[Jx-]

Thank you for this tool

I used this site before :

http://ptaff.ca/soleil/

iit can be usefull it show you hours of sun etc too

[GElite]

I totally see the benifit but trees and are going to greatly effect light. My grow is at th top of the highest hill around and is still shaded a large part of the day due to large trees. I can totally see using this program on sparsely vegetated land tho.

[trznk]

awesome tool!

 

Thanks a lot!

 

trznk

[Fran.gh]

Really useful tool for outdoor growers.

Thank´s for sharing.

Take care.