I mentioned nimbostratus in the Cloud of the Day post on altostratus, but I think it deserves a post of its own. It is a stratiform cloud that typically forms on a warm front. As advancing warm air rises over the retreating colder, denser air, we see the classical progression of cloud types. As the warm front approaches, we see the highest clouds first. Wisps of cirrus, maybe a layer of cirrostratus, complete with a halo, and cirrocumulus. Then, the closer the warm front gets, the lower the clouds we see. The middle etage clouds, altocumulus, and altostratus, perhaps even altocumulus castellanus, are next. Finally come the stratocumulus, stratus and the various forms of cumulus.
Public Domain
It is the stratus clouds that are of interest in the case of nimbostratus, because nimbostratus is so thick that it stretches from near the ground up into the middle etage. It is stratus and altostratus combined into one thick layer. It is so thick that its bottom is very dark, even black. It is so laden with water that precipitation is inevitable. The “nimbus” in the name has many meanings, but in the case of the cloud, it indicates that it’s a rain cloud.
Credit Indrajit Das – CC-BY-SA
Nimbostratus is the cloud that gives sustained rain over a wide area. It is the bringer of those dark, gloomy, wet days. Often there are fractus clouds scudding about underneath it. It’s the kind of weather that’s good for the lawn, and good for watching from inside, warm and dry.
Since the last report where the drought level was easing due to low temperatures and wet conditions, things are picking up again. While Droughtman seized the opportunity to point out that the wildfire hazard was low, it didn’t last. We’ve had a few hot, dry days and the scale is back up to very high, just short of an extreme hazard. — Breaking news: it just went up to extreme. — July was the only month to exceed normal during this period when we expect to get a good share of our annual precipitation, and it didn’t even reach 115%.
It looks as if the jet stream might be thinking of moving into its usual summer position, which is well to the north of us. When that happens we settle in for that long period of summer heat that we’ve usually had, or at least begun by now. This year, though, the jet stream seems to have stalled with an arm of it looping down to the west of us. That means there’s an avenue for a series of weather systems to pass nearby or right over us. Hence the lower temperatures and wetter weather.
The fire suppression crews got control of the big fire that was threatening to come over the mountain and descend on us. Those people are champs.
One of these times I’m going to have to talk about the deep duff.
Already we have surpassed the average rainfall for July, at only the three-quarter mark. This has allowed the drought level to be reduced from 3 to 2. That means our conditions have gone from “very dry” to “dry.”
What has Droughtman got to say about this? He says that 2019 has been very rainy, even though July has been the only month this spring/summer to reach normal levels of precipitation. He reiterates that the big lakes have a lot of water. To his credit, this time he didn’t say that means there’s no drought. Maybe he forgot to mention it.
Here’s hoping this unusually cool and wet July continues and carries over into August. It has been a nice change and we can use it. The wildfire hazard is down, a relief after the last two years of big fires. If we keep getting rain, maybe the aquifers will have a chance to recharge. With higher temperatures in the forecast, it would be good to build up a bit of a buffer.
We had a splendid thunderstorm pass through last night, with near-continuous lightning and some rain. Hopefully the lightning-caused fires can be knocked down before they do too much damage.
In the past week I’ve had a couple of visits from people who saw a link from another site to a post here. Being curious I backtracked them and found myself reading about the Great Cloud Conspiracy. Apparently when the International Cloud Atlas released a new edition with some added cloud types it meant that they were actually new clouds that didn’t use to exist. And of course that means that someone, probably the government, had done something that caused them to appear. Something about chemtrails? Note that my posts were linked to as a form of validation for their theories. In one case the author of the conspiracy post simply cut-and-pasted my post right off the screen. Any reasonable person who reads my posts will realize that I don’t subscribe to the conspiracy theories they’re supposed to support.
To be misunderstood is bad enough. To then be used as back-up for some wingnut’s conspiracy theory is going too far.