for astrophotography dark skies are very important but so are clear skies because
if the sky is covered in clouds you aren't going to get much astrophotography done
in other videos i've shown websites for finding a dark sky but i've never really talked about
how to best predict when it'll be clear so i thought i'd quickly review uh what i look for in
a forecast before i decide to make the drive out to a dark site and i'll be showing a few different
forecasting websites that i found to be good for my location in the northeast us like weather.gov
clearoutside.com and astrospheric.com and all the links for these are in the description so here we
go with my top tips and i'll also have a sort of bonus consideration at the end my number one tip
is the cloud cover forecast is the most important because if it's cloudy nothing else matters
i'd highly suggest not relying on one source for your cloud cover forecast i look at several and
only when the majority of these forecasts agree that it will be clear do i really trust it and all
these sites are basically using the same data i think from weather satellites but they use
different models to make the forecasts and i found when the models all agree on it being clear
then there's a much higher chance that it actually will be clear
my number two tip for me since i'm a mobile imager with no real protection against wind
the second most important thing to look at is the predicted wind speed and if it's saying over 20
miles per hour all night i'm much less likely to go out because i know without protection
those wind gusts are gonna give me elongated stars up here in the northeast those kinds of nights are
fairly rare but if i lived in a location where really windy nights like that were more common
i'd probably have to look into some kind of wind shelter i could quickly set up or just
bite the bullet and get an observatory my number three tip is that the temperature and dew point
predictions are usually pretty good and if the dew point is within a few degrees of the air
temperature that means high humidity and you're going to want to bring some kind of dew protection
ideally do heaters so that dew doesn't form on your optics because
once it does it's really hard to recover from that unless you have something like a hair dryer
and dew forms of course when the telescope is colder than the air temp just like when you have
a glass of ice water and there's little water droplets condensation forming on the outside of
the glass so the best tactic is a dew heater strip that keeps the lens or telescope just
slightly warmer than the air temperature all night and then dew should not form my number four tip is
it's good to know what transparency and seeing are but take those forecasts with a grain of salt i've
just never found them to be super accurate and as a deep sky photographer i wouldn't cancel a trip
just because the seeing or transparency is predicted to be poor because at least for my
location they're basically always poor for anyone that doesn't know these terms let me just quickly
explain them seeing is what causes the stars to twinkle or the planets to have that sort of jello
effect when you're looking at them what it is is it's the amount of turbulence in the atmosphere
and there are places on earth where the seeing is quite good typically if you are somewhere that's
really flat or or if you're a very high altitude like on a mountaintop you'll have better seeing uh
flat places are good because the air doesn't have to move around big obstructions like mountains and
being on top of the mountain like high altitude is good because then you're literally above
many of the atmosphere layers and all the lower atmosphere where a lot of the nasty
turbulence is happening transparency is in effect very similar to the effect of light pollution
it's a measure of how opaque or transparent the atmosphere is and so if the sky looks
brighter and murkier than normal that would be poor transparency and if it looks darker and
clearer with more stars visible that would be good transparency and my understanding is the
main source of transparency is humidity and moisture trapped in the atmosphere
and that's um what gives us poor transparency because the light pollution is basically hitting
a giant very thin stationary cloud in a way up there um and so you're seeing through this layer
of lit up moisture i think i'm running out of time here but my bonus consideration especially for us
north american astronomers right now is to look at smoke forecasts because this summer has been
the worst since i've started astrophotography out here on the east coast for wildfire smoke
keeping me from imaging and so i've started paying a lot more attention to these forecasts and what
i found is that um using the tool astrospheric if the smoke layer is showing like dense smoke
whether it's i see this purple color it's probably not worth setting up as long as it's
not dense like not purple or red then i'll still go for it but to be honest i'm still figuring
this stuff out myself and where that right cutoff point is well i hope this has been helpful this
has been Nico Carver with another five minute friday wishing you smoke free and clear skies