La Jolla - How To Find Surf and Wind Conditions

[Mr. NiceGuy]

Originally Posted by Denis_Ruso

I've been watching the weather and forecasts nearly daily for probably 10-12 years and have a pretty good understanding of weather/wind/swell/current etc.

But never even considered the conditions that cause fog. Can you explain this one a little more?

As a private pilot who flew a small Cessna 172 for about 10 years, I flew by VFR and dead reckoning (I fly in good weather by looking out the window and following landmarks.) I always looked at dew point and temperature during conditions and times of the year when it might have an impact on visibility.

In coastal areas of southern CA, depending on weather patterns, we sometimes have "May Grays" and "June Gloom" seasons. This is a time of year when fog can materialize because the air is full of moisture.

Dew point is when moisture sublimates out of the air into another form, such as fog. That point can be higher or lower depending on temperature and barometric pressure. When the two points are within 4 degrees of each other, we can suddenly find ourselves flying blind or in instrument conditions. Ditto for fog banks on the water.

On the water in a kayak, I look at water temperature, because that's a more accurate measurement of the air temperature just above the surface of the water than "air temperature" from weather reports which takes in other factors. However, that can be affected by air currents, so I'm talking about rough estimates and things to consider. That's why "4 degrees" is a rule of thumb for common sense flying and caution, because it's close to the dew point.

The amount of water that can be held in a gaseous state in the air is also related to relative humidity. Warmer air can hold more humidity.

https://www.livescience.com/43269-what-is-dew-point.html

https://en.wikipedia.org/wiki/Relative_humidity

I know very little about marine weather conditions for boating. Experience flying is different, I'm sure, but it still makes me think about these things. You should run your question under the nose of a good mariner, then report back so the rest of us can benefit from your curiosity.