Two weeks have lapsed since my last observation of the minnows. In typical north Texas fashion the weather has had its extremes since then, most recently ending in a 40+ hour stretch of freezing weather, ice, rain and snow. Today the sky is completely clear, however. The temperature is still cold with a light northwest wind. Tonight’s lack of cloud cover will cause even colder temperatures, which otherwise would have held in terrestrial heat radiation.
The water in the pond is cloudy from silt caused by the precipitation. Ice covers ¼ of the minnow’s calm area behind the rock where they have usually spent their time this winter. It’s fortunate that nature has allowed ice to float. In sinking it would instead cover the floor of any body of water killing all life. However today the only life appears to be the algae. There is not a single minnow in sight dead or alive. Their disappearance is a mystery. It may be weather related. The only living thing observed besides plant life is a single squirrel burying a nut by a bare tree. Weather in north Texas is volatile. It is the section of the country where air masses collide. Winter typically holds a grip through mid-March. On March 8, 1989 north Texas had one of its worst ice storms in history shutting down I-35 from Denton to Oklahoma City. In late February to early March in 1836 the defenders of the Alamo not only had to contend with 2000 Mexicans but also an “Alberta Clipper” pushing south through San Antonio causing intolerable cold on their final night. All of nature is effected by weather. It drives the decision making process of much of the animal world. Humans, however, have the power of observation over time to give us clues of what’s coming. Years of flying aircraft have made me especially interested in weather.
For instance in the northern hemisphere, when one stands with their back to the wind, low pressure is always on the left. Low pressure is where fronts are born and fronts are then driven by the jet steam. Today for example the wind is from the north putting low pressure to the east represented by a passing snow storm (low pressure) that dropped one to two inches of snow in some places. In the summer, strong southerly winds signify a strong low pressure zone to the west. During the summer this is usually caused by a dry line in west Texas that separates high dry desert air from the moist gulf air of east Texas. Also called a “Marfa front” (due to its proximity to the west Texas town of the same name), this dry line oscillates back and forth across the west Texas prairie during summer….a sort of permanent low pressure system. It can move far enough east to effect Dallas and cause violent thunderstorms as the heavier dry air forces moist gulf air aloft. Texas for the most part has no orographic lifting (mountains) to cause this lift but a dry line is just as effective. If a Marfa front is combined with a rare summer cold front passing through the area tornadic activity is likely.
We are approaching a transition in Texas weather. The earth is starting to get further away from the sun while the earth’s tilt is pushing Texas more directly into the sun’s rays. Though farther away, the Sun’s rays bearing down directly overhead will soon heat up the Texas countryside. Initially this will cause violent spring thunderstorms due to unstable air masses colliding. Later in the summer, storms will usually be of the single air-mass variety if any develop. For now cold fronts still have the power to reach Texas. A fast moving cold front smashing into warm moist air can cause barometric pressure gradients to resemble a contour map of the Rocky Mountains. Steep! The steeper the more violent. Sometimes the collision is so violent the cold front shocks the air ahead of it into a pre-frontal squall line with green roiling clouds and very large hail. An observer on the ground might think the worst is over when it passes only to be hit even harder when the front actually arrives. All of these things will affect the mandala and its observer in the coming weeks.
A sketch of Spanish yucca by the pond this week. It’s dagger like leaves from a lattice for tall dead grass.
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