Spring is a great time of year. I always look forward to it, and so far, it has not disappointed! While there are the usual fits of warmth and cold, the season is moving forward. Soon we’ll be wishing for cooler days.
One of the great attributes of spring is dramatic weather. There are times I make a point not to check the forecast before going to bed, so what is before me is experienced without expectation. A bit weird perhaps, but I like it.
How weather patterns manifest themselves this time of year is noteworthy. I fear that for much of my life, I had my head down, busy with the task or interest at the moment, and I missed some beautiful scenery and conversations along the way. Not so the other day. Maggie and I were driving into Salt Lake Valley, only to be pleasantly surprised with the spectacular snow-capped Wasatch Front. You may ask, “What’s the big deal about that? I see snow on the Wasatch Front for most of the winter.”
Indeed, you do — but not like this. The wind had died down, and apparently it had been calm overnight. The temperature had cleanly split, with cold, moisture-laden air above, and warmer air below. The result was a clean line, extending north and south, for 50 miles or more. White above, bluish-green below. It was almost like you were looking at a giant painting, and you could almost see the artist’s signature in the right-hand lower corner: God!
Not all weather events are as pleasant. In fact, many can present a challenge. A late cold snap is never welcome news for the orchardist or veggie gardener, but it’s part of the deal from time to time. If we’re smart, we’ll work to be prepared for such things. And, there’s nothing like being awakened in the middle of the night by claps of thunder, lightning stabbing down all around you, and the roar of hail pelting the house and windows.
Such was our experience not too long ago. I have a confession to make: I acted like I was sleeping a lot deeper than I was. Maggie let me know at daybreak that she had the “delightful” experience of sitting up with a couple of frightened dogs for an hour or so. I’m confident that should the call from the dogs come again at night, it’ll be my turn.
This year, I’ve made the conscious effort to understand more about weather terminology and how weather patterns work. Why not? As a gardener and someone who enjoys being outside around our place, weather means a lot to me. To that end, I purchased the National Audubon Society’s Field Guide to the Southwestern States.
What a resource! This edition is applicable for Arizona, Nevada, New Mexico and Utah. What intrigues me a lot about this guide is that it doesn’t have one emphasis. Instead, there is an integrated approach that makes data and information in one area applicable in another.
Remember flora and fauna from your science education? It’s right there, telling of common plant and animal life, including range of habitat, diet, identifying traits and so forth. But it doesn’t stop there.
Constellations of the stars, navigation, elevations, minerals, and of course, weather patterns and terminology all abound. Couple that information with lots of great photos and multi-colored charts and this little book becomes a must-have.
Stick with me while I tell you some of my favorite weather tidbits. Let’s talk about humidity first. We’ve all experienced varying levels of humidity. Simply put, absolute humidity is the actual amount of water vapor contained in a given amount of air. A more common term is “relative humidity” (RH), which is the percentage of water vapor contained in a measured volume of air at a specific temperature.
Have you ever said, or heard someone say, “The humidity’s 110 percent right now!”? In actuality, you can’t get more than 100 percent humidity, no matter what the temperature, volume of air or availability of water. Once you approach 100 percent RH, condensation in some form will occur. This is closely related to dew point, but let’s limit our plunge into geekiness for now.
I’ve mentioned in this column before that you can see evidence of how much water is in the air by the appearance of steam plumes either at the fish food plant, or the Praxair complex on SR-201. If the steam immediately disappears when it emits from the stack, then the humidity is low and the air eagerly absorbs the moisture. If the vapor billows out of the stack, and piles up into a column, then the air is saturated.
One of my favorite man-made phenomenon are contrails left by jet-powered aircraft. For a contrail to occur, certain conditions have to exist. This includes the right blend of temperature, altitude and humidity.
A jet operates because a large volume of air is ingested through the engine’s intake. A series of fans compress all that air into a small chamber. Fuel is then injected at the precise moment and pressure, resulting in what can best be described as a continuous explosion. This generates a tremendous amount of thrust and a column of highly-compressed gas comes out the rear of the engine.
That is when the contrail is generated. The air temperature at 30,000 feet above sea level is cold. So as the hot gas comes out, it quickly cools to the ambient air temperature. When it does, it can no longer hold moisture. The humidity evidences itself by creating a cloud trail. Eventually, the vapor will reabsorb back into the surrounding air.
Lastly, one of my favorite views is when it’s beginning to rain in the middle of a hot summer day. Virga can be generated. While you may not have known what it’s called, you’ve likely seen it. This is when rain falls out of moderate altitude clouds, but evaporates before hitting the ground.
Humidity again comes into play. As the temperature under the cloud drops, rain starts to fall. This increases the speed of the temperature decline, creating even more rain. However, once the rain is away from the cloud, it may encounter warm air that hasn’t cooled yet. The warm air can hold a lot of water vapor, so the drops can be reabsorbed. One of the most dramatic weather photos I’ve taken was just after the temperature had equalized all the way from under the cloud to the earth’s surface. Once that happened, a virtual wall of water appeared. Awesome!
So, as the season progresses and you find yourself outside more, be sure to look around. If you do, you may see some really cool things that others less observant may miss.
Cooper can be contacted at firstname.lastname@example.org, or you can visit youtube.com/dirtfarmerjay for videos on gardening, shop skills, culinary arts and landscaping.