I assume they are always out there in the summer, that the spiders don't wait until those conditions to set about their busy work. But it takes that perfect combination of dew and sun to make such a pretty picture.
I could see hundreds; half an hour later the sun was high and the webs had once again become humble and obscure. Some things on the farm demand immediate attention, like a predator near the chickens or the cows escaping. Other things demand immediate attention so you don't miss a show like this.
It's good to remember to take the time to smell the roses ... or see the spiderwebs.