Wednesday, December 31, 2014

Relative Humidity

Humidity is measured as a percentage, or in other words, the amount of moisture in the air compared to the maximum amount of moisture that the air can hold. When humidity is at 100%, the air can no longer hold any more moisture, at which point precipitation will occur.

Humidity is  measured as a percentage, but the percentage is relative to temperature. What this means is when the outside air is warmer, it is able to hold more moisture. On the other hand, when the outside temperature is colder it is unable to hold as much moisture. The relative humidity will fluctuate during the day as the temperatures fluctuate. For example, if humidity is at 80% in the evening and the temperatures begin to drop, the relative humidity will increase because the cooler air will not be able to hold as much moisture. In this example, when the humidity reaches 100% we call that the dew point, or the point at which dew begins to form.

Relative Humidity is Measured as a Percentage

You probably are finding this interesting (or not), but what does this have to do with fruit trees? I am often ask, "How much should I water my fruit trees?" Well the answer to this question depends on many variables, like the type of tree, the soil type, your specific climate and the time of year, even the location of the tree in your garden. Another important factor in determining how much water your fruit tree will need is... you guessed it... relative humidity.

When humidity is high, evaporation and transpiration occurs at a slower rate, when relative humidity is low it will occur quickly. Knowing the relative humidity in your area could help you better determine how much water your fruit trees will need and how often they will need it.

So the next time your listen to the weather forecast keep an ear open for the relative humidity and the dew point in your area and see if this information will help you better formulate a watering routine for your fruit trees.

If you have additional questions regarding this information, please email me at or comment below.