A Year of Iowa Nature: Discovering Where We Live

September

September 92 MARES’ TAILS ST Thin gossamer cirrus clouds generally indicate a change in weather and often precede fronts that move from west to east. They form about five miles or more above the earth and are composed of ice crystals. They are commonly called mares’ tails due to their shape and form, which changes constantly due to strong upper level winds or wind sheer. A curtain of snow or ice crystals often precipitate from them, but it soon evaporates. Late in the day they can produce spectacular sunsets. 94 CLOUD-TO-CLOUD LIGHTNING ST All of us have had the opportunity to observe lightning in daylight and in darkness, in the distance and likely when it was too close for comfort. Lightning is an immense charge of static electricity between a positively charged cloud and the negatively charged earth’s surface. Lightning within clouds or between clouds is actually more common than cloud-to-ground lightning.If it occurs within a single cloud,it is called intracloud lightning.If it occurs between clouds, it is intercloud lightning. This effect is also sometimes called sheet lightning since it may not be possible to see the actual lightning streak. 96 A BIRD IN THE BUSH ST The old proverb, a bird in the hand is worth two in the bush, urges us to be satisfied with what we have and not yearn for more. When it comes to watching birds, a bird in the hand is not very likely and even two or more in the bush may be difficult to identify. Migrating warblers, such as the common yellowthroat, are heading south to keep up with their insectivorous food supply. On an early morning foray they may be just one of a host of small birds that we can find creeping through heavy undergrowth.Whether it is on the edge of woods or in tallgrass prairie, a glimpse is often all we get. Sometimes it is hard to be satisfied. 98 MONARCH MIGRATION ST Monarchs in autumn migration frequently gather to roost in late afternoon . After feeding on late summer flowers such as goldenrods, they begin to float in like autumn leaves. Roost sites generally tend to be out of the wind on the leeward side of a woodland.New arrivals often elicit a response from the group as they settle in.A wing fluttering action often travels across the group;however, this may cause them to momentarily take flight. 100 MORNING DEW ST Clear skies, little or no wind, and falling temperatures in early autumn create perfect conditions for heavy morning dew on the prairie. Species such as Indian grass may succumb to the weight of the water. Both birds and mammals often try to avoid the tall wet vegetation and move into open areas, mowed lanes, and grazed pastures. Without waterproof pants and a jacket, a person easily becomes soaked to the waist and chilled. Yet it is just this appeal that urges one to go out, look, and listen. ...