That's often the $64,000 question, right? After waiting (and waiting) for challenging conditions to improve, is it prudent to invest still more time in a specific location - or is this session just not going to yield a result? Maybe you'd have better luck tackling something else on your shot list.

Obviously, there's no way to know for sure.

The better acquainted you are with the area, including an understanding of its micro-climate, the more prepared you'll be to make that call. (Certainly your objectives will factor into the decision as well.)

Fog is one of those interesting elements that can throw a monkey wrench into the mix. Don't get me wrong: who doesn't love fog? It can add a great deal to a scene. There are some locations at which I decide to work specifically because I'm expecting early morning fog. No fog, no photograph.

That said, fog has a mind of its own. Sometimes there's too much of a good thing: it can be extremely dense and linger for hours. By the time it burns off, the sun has risen too high in the sky and the light is too harsh. Or conversely, perhaps it's in too much of a hurry to leave and dissipates very rapidly.

Over the past week, I've had two challenging sessions in Grand Teton National Park in which the hoped-for fog played a factor, and each time I had to weigh whether or not it was worth hanging around. On both occasions I opted to remain - though I was unable able to make the photographs I had imagined.

Both times I expected fog. In the early mornings following rainfall it's typical to see fog over portions of the valley. On the first day, it was still raining steadily two hours before sunrise and continued to sprinkle off and on after that. I got the hoped-for fog....and then some. The mountains were completely obscured.

Ultimately, it took more than seven hours for it to finally lift completely and reveal the tops of the peaks. Yet I remained because the dense, often-changing blanket presented a variety of alternate compositions, both in front of and behind me. Interesting weather is one of the things that can help photographers create unique images in overly-photographed places like national parks.

Four days later at the same location, I remained because I was there specifically to try to take advantage of potentially fleeting conditions. Early snowfall had just draped the Tetons in white. Many of the trees were at or near peak color. I wanted to capture that mix of autumn and winter - but the window wasn't open very wide. Heavy winds forecast for the coming days could quickly sweep the colorful foliage to the ground. There was a chance for more precipitation on the horizon.

This time of year, precipitation often brings with it very low ceilings which completely obscure the mountains. This session could be my only opportunity. The decision to stay was easy.

Each time I could have walked away empty-handed.

However, knowing what to expect in terms of conditions in the park, and based on what I wanted to accomplish, it made it easier to decide how to manage my time.

We don't always have the luxury of working an area we know well. In that case, do as much research as you can ahead of time. Depending on where you're headed, there's often a great deal you can learn online. Once you hit the ground, spend the first day scouting the locations you've designated on your shot list.

What you glean when you actually see them for yourself - combined with your knowledge of weather patterns/behavior - will help you further crystallize your plan. Sometimes waiting for seven hours is the thing to do. Other times, it's wise to cut your losses and move on.

Just don't give up on a location too quickly.