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Putting the Land Back In Climate

What if we’ve been looking at the climate, well, incompletely? What if there’s another side to climate change, one less concerned with what we put in the atmosphere than what we do to the land, a side which, despite four decades of climate education, has yet to be explained to us?

Scientifically speaking, there is. Scientists call it “land change,” a characteristically neutral term for the not-so-neutral ways humans alter landscapes, through things like logging, agriculture, road building and urban/suburban sprawl. By disturbing land this way, we disturb the land’s ability to hold and cycle water, and that affects climate, particularly on a local and regional level.

Though we tend to think of climate in terms of carbon, water is in fact the primary medium of Earth’s heat dynamics, perhaps not surprising on this 71% water planet. Water not only has the highest heat capacity around, it’s also a shapeshifter, continuously phase-changing between water, vapor and ice, absorbing and releasing heat at each juncture, elegantly distributing heat along the way.

Evaporation, the phase-change from water to vapor, is a cooling process. We’ve all felt it when we sweat. Plants essentially do the same thing when they respire, cooling themselves and their surroundings by releasing water vapor from under their leaves. Trees are the power lifters here, drawing upwards of 150 gallons per day through their roots and out through their leaves, giving an average tree the cooling power of two air conditioning units running all day.1

The vapor, with the heat held latent inside it as a chemical potential, rises until it is high and cold enough to condense back into clouds and rain, at which point the heat is released into the air again, only higher, some of which continues its journey out to space, the rest reentering the system elsewhere…

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Water Woes

Water Woes

If you live in a place where water falls from the sky during summer this blog is perhaps not so helpful. However, gardeners in much of the western United States will suffer this summer from hot days (sometimes record breaking) and will need to irrigate their gardens and trees in order for them to survive impending drought conditions. The ongoing drought has drained reservoirs and flows of rivers are down or, in some cases, dry entirely. Due to water scarcity, purveyors are restricting water use outside of homes and in some cases curtailing all landscape irrigation. Using water wisely in the landscape has never been more relevant than now. In this blog post we’ll continue to explore saving our gardens from drought and touch on water use, water demand and plant stress.

Good news — Bad news

The good news is that the longest day of the year was last month. That means that the days are ever so gradually getting shorter. As days shorten, plants use less water. Water use is tied directly to photosynthesis and when the lights are out there is no photosynthesis. Shorter days mean less demand for water. The bad news is that we may have record breaking hot days ahead. Plants become susceptible to wilt, sunburn and dieback during very hot weather. The best way to prevent this is to ensure that roots are moist during very hot weather.

The combination of drought and heat caused sunburn to these privet leaves

Mediterranean Climate

It turns out that in Ventura, CA the longest day of the year is one of the historically driest months (least rainfall) and the shortest day occurs in a month with more rain than average…

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“How dry I am “: Four types of drought and how they can affect gardeners and gardens

“How dry I am “: Four types of drought and how they can affect gardeners and gardens

Linda’s post last week about “drought-resistant” plants made me think about drought and how different types of drought affect gardeners in different ways. In her article, she defined drought as “an unusual lack of rainfall”. This is one of four different kinds of drought that climatologists talk about, and I thought it might be interesting for you to hear about how the four (or maybe five) types of drought differ and how they affect gardeners in diverse ways. A great source of drought information across the U.S. is https://www.drought.gov/.

360° panorama of the northern end on the lake bed of a drying Lake Albert in Wagga WaggaNew South WalesAustralia, source: Bidgee, Commons Wikimedia.

Meteorological drought

The first type of drought, the one Linda described last week, is what climatologists consider a meteorological drought. A meteorological drought is related to how much rain you get compared to usual conditions at your location. I like to think of it as “too many days of nice weather in a row”, since in these dry conditions, the sun is shining and it is a great time to garden, play golf, or do construction. Of course, if you don’t get rain for a long time, you start to see impacts on plants, water bodies, and wells, but meteorological drought is usually not identified in terms of impacts, just on the amount of precipitation measured over weeks, months or years. Meteorological droughts look different depending on where you are. It is possible to have drought even in a desert if rain does not fall over an unusually long time…

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“Cry Me A River”

“Cry Me A River”

I got a Facebook message early this week from a friend in Sacramento CA that said after over 200 days with no rain, she got 4.83 inches in a 24-hour period from the latest extreme rainfall that occurred over northern California. Others have reported up to a foot of rain in three days. If you follow the news, you may have heard the term “atmospheric river” used to describe the torrential rains and flooding that have occurred this week in San Francisco and other parts of Northern California. In this post, I want to explain what atmospheric rivers are and how they affect rain climatology in the Western U.S. as well as other parts of the United States and the world.

Tahquamenon Falls–Autumn. Source: Wfgc, Commons Wikimedia.

What is an “atmospheric river”?

The term “atmospheric river” first appeared in the modern scientific literature in the early 1990s. Since it was first used, there has been a lot of discussion about what the term actually means. Commonly, it is seen as a band of very moist air flowing into a coastal area, bringing the potential for a lot of rain to the region that is at the downwind end of the flow. In some respects, it is like being on the receiving end of a firehose streaming high-intensity water right towards you! After a lot of discussion by meteorologists (described in this Bulletin of the American Meteorological Society article) the official definition in the Glossary of Meteorology became:

Atmospheric river – A long, narrow, and transient corridor of strong horizontal water vapor transport that is typically associated with a low-level jet stream ahead of the cold front of an extratropical cyclone. The water vapor in atmospheric rivers is supplied by tropical and/or extratropical moisture sources…

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Dying crops, spiking energy bills, showers once a week. In South America, the climate future has arrived.

An aerial view of the drying bed of the Paraná River in August as the water reached a historic low near Rosario, Santa Fe, Argentina. (JUAN MABROMATA/AFP via Getty Images)
BUENOS AIRES — Sergio Koci’s sunflower farm in the lowlands of northern Argentina has survived decades of political upheaval, runaway inflation and the coronavirus outbreak. But as a series of historic droughts deadens vast expanses of South America, he fears a worsening water crisis could do what other calamities couldn’t: Bust his third-generation agribusiness.
“When you have one bad year, you can face it,” Koci said. Some of his 20,000 acres rest near the mighty Paraná River, where water levels have reached lows not seen since 1944. On the back of two years of drought-related crop losses, he said, the continuing dryness is now set to reduce his sunflower yields this year by 65 percent.

“When you have three bad years, you don’t know if there will even be another year,” he said.

From the frigid peaks of Patagonia to the tropical wetlands of Brazil, worsening droughts this year are slamming farmers, shutting down ski slopes, upending transit and spiking prices for everything from coffee to electricity.

So low are levels of the Paraná running through Brazil, Paraguay and Argentina that some ranchers are herding cattle across dried-up riverbeds typically lined with cargo-toting barges. Raging wildfires in Paraguay have brought acrid smoke to the limits of the capital. Earlier this year, the rushing cascades of Iguazu Falls on the Brazilian-Argentine frontier reduced to a relative drip.

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Heat domes, wet spells, and the weather patterns that tie them together

Heat domes, wet spells, and the weather patterns that tie them together

Do you have a favorite kind of weather that you love to experience? For me, it’s the first warm evening of spring, when the air is just warm enough and the wind just strong enough for the air to feel as though it is dripping off my fingers. On nights like that, I can tell that the air really is a fluid, the topic of this week’s blog.

The wind of spring, Toshihiro Oimatsu via Commons Wikimedia

What causes atmospheric weather patterns?

You may have noticed this year that the weather patterns across both the United States and Europe have been very persistent. That has led to the occurrence of record-setting high temperatures in some locations like the Pacific Northwest and the central US and southern Europe as well as day after day of rain in the Southeastern US. Both of these weather patterns have caused no end of grief for gardeners and farmers, since weather is seldom stuck on day after day of “perfect” conditions (even if you could define what those are).

To understand how weather patterns get stuck, it helps to know how the air moves through the atmosphere. Wind is driven by differences in heating between two areas. That contrast leads to differences in density and pressure between the areas, and the air flows from higher pressure to lower pressure to try to equalize the amount of air between those areas. The large-scale weather patterns across the globe are caused by differences in the sun heating the spherical earth at the equator and at the poles at different angles due to latitude. There are also smaller-scale wind circulations due to differences in heating between land and water (oceans or lakes) that cause the same movement of air molecules…

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A New Global Tinderbox: The World’s Northern Forests

A New Global Tinderbox: The World’s Northern Forests

Rapidly rising temperatures, changes in precipitation, and increased lightning strikes are leading to ever-larger wildfires in the northern forests of Alaska, Canada, and Siberia, with potentially severe ecological consequences.


Ted Schuur has spent the better part of his career making the connection between climate change and wildfires that are burning an increasing amount of land in Alaska and in sub-Arctic and Arctic forests around the world. So the Northern Arizona University scientist wasn’t all that surprised this summer to find his field stations in the interior of Alaska surrounded by fires on three sides. At the time, the state was well on track to recording its second-worst fire season ever.

Alaska Fire Service
Alaska experienced its second-worst fire season in recorded history this summer.

The surprise came in mid-summer when Schuur took a few days off from his research to attend a meeting in Colorado. He had hoped the trip would give him a break from Alaska’s noxious smoke. The smoke in Boulder, however, was so thick that the state’s Department of Public Health and Environment was advising parents with young children and people with heart disease and respiratory problems to limit their outdoor activities.

As Schuur soon learned, the pall of smoke in Denver had actually drifted down from a large number of forest fires in the Pacific Northwest and Canada. “I’ve never seen anything quite like this summer,” says Schuur. “It seemed like half the continent was on fire at one time or another.”

Schuur wasn’t exaggerating. In June, as many as 25,000 men and women were fighting thousands of wildfires that were burning out of control in states such as Alaska, Washington, California, and Idaho, and in the Canadian provinces of British Columbia, Alberta, and Saskatchewan.

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Beyond the Perfect Drought: California’s Real Water Crisis

Beyond the Perfect Drought: California’s Real Water Crisis

The record-breaking drought in California is not chiefly the result of low precipitation. Three factors – rising temperatures, groundwater depletion, and a shrinking Colorado River – mean the most populous U.S. state will face decades of water shortages and must adapt.

The current drought afflicting California is indeed historic, but not because of the low precipitation totals. In fact, in terms of overall precipitation and spring snowpack, the past three years are not record-breakers, according to weather data for the past century. Similarly, paleoclimate studies show that the current drought is not exceptional given the natural variations in precipitation of the past seven centuries. Nor can it be confidently said that the current drought bears the unequivocal imprint of climate change 

Oroville Lake

Mark Ralston/AFP/Getty Images
The Lake Oroville reservoir in Northern California was at less than 25 percent capacity last month.

driven by increasing greenhouse gases, since the low precipitation is well within the bounds of natural variability.

All this being said, it is also clear that this drought is exceptional and should be seen as an historical turning point. Indeed, California is moving into new — and worrisome — territory for three reasons: rising heat, which causes increased evaporation; the continuing depletion of groundwater supplies; and growing water shortages on the Colorado River, the main external source of water for Southern California.

A decade ago, I first wrote about California and the “perfect drought.” Now, unless bold steps are taken to deal with a growing water crisis, California may be facing a future of perfect droughts. 

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