City Creek Nature Notes – Salt Lake City

July 19, 2017

July 18th

Radio Tower Run and Anti-wind

8:30 a.m. In the morning air, I begin one of my more favorite canyon jogs: the Radio Tower run. This track begins at lower Pleasant Valley at mile 1.3, ascends straight up the natural gas pipeline road to the western ridge of the Salt Lake salient, down to a set of large microwave radio towers on the ridge, and then returns via the Bonneville Shoreline Trail to Guardhouse Gate. The total physical distance is about five miles, but in spirit is longer. The trip begins with a half-mile hike up a forty degree slope through Gambel’s oak and Cheat grass, but one is rewarded by increasingly improving views of the urban city below. At the ridgeline, there are several acres of Kentucky bluegrass and in prior years it was not unusual to find a morning or evening moose grazing in the field. This year, there is no moose, but as in prior years, I again flush a pair of Greater sage grouse (Centrocercus urophasianus) from the undergrowth. Commanding views of Wasatch Mountain Front Range, Salt Lake City, the Oquirrh Mountains, and the Great Salt Lake coupled with cooling, strong ridgeline breezes release the mind. Descending along a fire road to the Bonneville Shoreline Trail, I next follow the Trail horizontally through two dense valleys of Gambel’s oaks that are hidden behind Ensign Peak. These are the breeding grounds of the local population of Black-billed magpies (Pica hudsonia), and consistent with their curious personality, one or two break from their continuous challenging cawing to give me a brief inspection. By now the combination of increasing heat and exercise begins to take effect as I descend the last leg of the trail as it crosses a pass and descends back down into City Creek Canyon. The trail passes under ledges of brown sandstone created from the erosion of a vast, but now disappeared mountain range in Nevada (January 7th). In past springs, cliffs have hosted Red-tailed hawk (Buteo jamaicensis) nests. Before noon, I am tired but happy to reach the water fountain at Guardhouse Gate. An afternoon down canyon breeze provides more cooling.

* * * *

Because of its unique geography and proximity the Great Salt Lake, the first 1.2 miles of City Creek Canyon Road is subject to unusual anti-winds (Steenburgh 2016). The direction of winds through mountain canyons are normally thermally driven by the relative temperature of the surrounding mountains and the valleys below. As with high and low pressure weather systems, wind moves away from the center of a region of hot, high pressure air. In the afternoon when flat valley floors are hotter than the surrounding cool mountain ridges, up-canyon anabatic wind blows. Down-slope katabatic wind blows at night and during the mornings away from the mountains when the mountain air is relatively hotter than valley floor air (Whiteman 2000). Any long-distance weekend bicyclist in northern Utah are aware of these winds. When pleasure riding up-canyon in the mornings, the katabatic winds produce fierce headwinds, and then in the late afternoon, when returning home down the canyon, a rider is met by strong anabatic headwinds. The afternoon winds can be near hurricane force. I remember a few unique experiences in the 1980s and 1990s of be unable to pedal downhill against anabatic winds even though I stood up on the pedals and pressed downward as hard as possible.

Meteorologist Steenburgh of the University of Utah notes that the geography of City Creek Canyon generates antiwinds that blow down-canyon during the heat of the day (Steenburgh 2016). The western ridge of the Salt Lake salient is higher than the eastern Avenues ridgeline. Afternoon cool breezes flow off of the Great Salt Lake from the west to the east across the lower canyon. This induces wind in the canyon to overwhelm the usual afternoon up-canyon anabatic wind, and antiwind, or wind that is flowing downcanyon against the normal direction of anabatic wind, results.

The Great Salt Lake breezes that cross over the western and eastern Salt Lake salients may explain why so may soaring birds are seen transiting the canyon. The west-to-east cross breeze allows them to tack up wind and up canyon like sailboats. They can either again climb the south-eastern salient as the breeze turns upward off the ridge, or they can shoot down canyon along its middle and riding the anti-wind.

* * * *

On July 18th, 1934, 74 citizens, as part of military training at Fort Douglas, hiked up City Creek Canyon (Salt Lake Telegram). On July 18th, Waterworks Superintendent F.L. Hines boasted at a national convention that Salt Lake had some of the purest water in the nation (Salt Lake Telegram).Salt Lake had some of the purest water in the nation (Salt Lake Telegram).

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1 Comment »

  1. Thanks John. I’m thinking about it.

    Comment by canopus56 — July 24, 2017 @ 6:36 pm


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