Today I will be talking about weather fronts and systems, as the vague title might have suggested to some of you ;). Weather fronts are boundaries between two masses of air of different densities. I will discuss the different fronts and pressure systems today. I will also talk about how these are used to forecast the weather.
A cold front is the leading edge of a cool mass of air (I don't mean that the air is super popular, I mean 'brrr'). On a weather map, it is show as a blue line with triangle on the line pointing the direction of travel of the front, as you can see on the left. Cold fronts are made of cold air, so they push up the warm air, causing lowered pressure along the cold front. See the diagram below.
The lowered pressure means that a cold front will generally be accompanied by unpleasant weather, such as thunder storms or just a cooling of the temperature. A cold front moves faster than a warm front. A cold front usually has a high pressure system, so meteorologists can look at a weather map and find the location of a cold front to determine what the weather will be on a given day.
A warm front is the leading edge of a warm mass of air. On a weather map, it is shown as a red line with half-circles pointing in the direction of travel. A warm front is made of warm air, and as it approaches, rainfall steadily increases. It has a lower pressure than cold fronts, so it moves slower than a cold front would. As warm fronts usually have a low pressure system, meteorologists can determine the weather at a given time, same as they would with a cold front.
Today I will be talking about weather folklore and proverbs. (again with these cryptic titles, sheesh;) I will discuss ten different weather proverbs and whether (ah ah? :)) or not they are accurate.
I'll start with one of the most well-know proverbs, "Red sky at night, sailors delight; red sky in morning, sailors take warning." This proverb is mostly true as red has the longest wavelength and it can break through thick concentrations of dust and moisture. When those concentrations causes red at night, when the sun is setting, this implies a high pressure system moving from the west which generally means good weather. If, however, the highest concentration is in the morning, when the sun is rising, that implies that there is a high pressure system that has already passed, and a low pressure system is likely to follow. As I have told you before, low pressure systems equal verrry unpleasant weather. You can view a fuller explanation at the Library of Congress' archive here.
Next proverb is a bit simpler: "Clear Moon, frost soon." This proverb uses the fact that when the atmosphere is free of clouds, "Clear Moon", there isn't a extra insulating layer of clouds to keep in the heat, which could cause the temperature to lower enough to form frost. Now, this proverb isn't that accurate, because you could have a cloudy winter day that produces frost, and you could also have a clear, warm summer day that doesn't produce frost, even though the sky was clear. So, this proverb is only accurate some of the time in late fall. To be more accurate, it should be re-written as "Clear Moon in late fall, frost is more likely to form". I wonder why they haven't switched to that yet? ;)
Third proverb: "A year of snow, a year of plenty". This proverb predicts that if there is constant snow fall during the winter, with no frequent thaws, then the next year's harvest will be plentiful. It is true that the soil will be more fertile if there aren't frequent thaws and freezes, and that less crop seeds will be killed when the ground remains frozen. Constant temperature throughout the winter also prevents fruit trees from blossoming before the killing frost season is over.
Fourth proverb: "Crickets are quiet, rain's a comin'" (ok, ok, I made that one up...) Even though you may not have heard this proverb, it is a good example of using nature to predict the weather. Cicada's are not able to vibrate their wings when the humidity is very high, so this could be an indication of rain coming soon.
Fifth proverb: "You can find the air temperature to within 1 degree of accuracy 75% of the time by counting the amount of crickets' chirps within a 14 second period and adding 40." That is an actual formula, and is very neat to find out. If you want to see a scientific explanation for this phenomenon, you can go here. The scientific article is here.
Sixth myth: "If a groundhog sees its shadow on groundhog day, there will be 6 more weeks of winter." This is a myth, plain and simple. There is no scientific evidence to support the theory that a cloudless day on groundhog day means that there will be six more weeks of winter. In Saskatchewan, though, winter doesn't end until the middle of March anyways, so groundhog day is kind'a pointless.
Seventh myth: "When cats sneeze, it's a sign of rain." Okay, this is just ridiculous. Sure, the extra static electricity in the air before a thunder storm COULD cause the fur on a cat to stand up, tickling its nose, causing it to sneeze; but REALLY? That myth is ridiculous. Cats sneeze for the same reason everything else does, something is triggering the sensor on the inside of the nose. God didn't create cats' noses to sneeze to predict the weather and not do anything when their nose is irritated with dust or other particles. This myth is just too ridiculous, so on to the next one.
Eighth myth: "Onion skins very thin Mild winter coming in; Onion skins thick and tough Coming winter cold and rough". This myth relies on selective memory, as when it is true, it is well remembered; but when it is false, it isn't important enough to remember that it didn't come true that particular year. That being said, there is some truth to it, as if a year generally has less moisture, the onion's skin will be thinner due to lack of moisture, and the winter will probably be more mild, as there is less moisture for it to hurl at you. So, all in all, this is a myth, but it does have a bit of science to it.
Ninth myth: "The squeak of snow will the temperature show." This is partly true, as the colder the temperature of the snow, the louder the crunch. You can see a scientific explanation for that here.
Final myth: "When ditches and swamps offend the nose, look for rain and stormy blows.". This is actually a fact; when you can smell that smell, you know it is going to rain. Now, you may think that it has something to do with atmospheric pressure and that cow farm down the road, but it doesn't. (Am I sure that it has absolutely nothing to do with the cows? Um, mostly...) The actual reason is that a bacteria called geosmin lives in the soil in moist conditions and when it dries, it produces spores to survive to the next rainfall. When rain falls on them, they rehydrate and the smell is produced. The reason we smell it during a rain, is because the particles in the soil release the smell as it rains in a location away from you and the wind blows the particles to you. You may be thinking, But how does it stink so much?! Well, its because the human nose is very sensitive to them; it can pick it out if there is just ten parts in a trillion. If you would like a bit more detailed report on them, you can check this out.
So, that was my post on weather proverbs and myth. See you next time!
Today I will be talking about the differences between radar and satellite weather technologies.
Satellite weather technology uses pictures taken from a weather satellite to determine cloud cover and global weather systems. This allows meteorologists to look at the global weather systems to more accurately predict local weather. In essence, weather satellites would be used to look at the global weather to help predict local weather while radar would look at nearby local weather to predict upcoming local weather. (Did I say weather enough in that sentence? These blogs are getting monotonous... :() You can see a picture of North America taken from a weather satellite on the above.
Radar weather technology uses radar stations to generate a weather map of the local region. This weather map, complete with the moisture content of the clouds, helps meteorologists determine what the short-term local weather is going to be like. You can see a time lapse of hurricane sandy from a weather satellite below, along with a 7 month time lapse of US weather radar images. Sorry, couldn't find one for Canada.
Today I am talking about weather forecasts. I will show you weather forecasts from three different sources and discuss the differences between them. The first forecast for Regina is from The Weather Network. TWN forecasts that the high for tomorrow will be 0°C, and the low, -17°C. The Weather Channel's forecast has a bit less of a gap, predicting a high of -1°C and a low of -8°C. Finally, the Weather Office of Canada predicts a high of -2°C and a low of -17°C.
There isn't that much of a difference in the three forecasts, except for the Weather Channel's. The Weather Channel, however, is based in the US where they don't have to figure headaches like windchill out. This explains why their low for Monday is a full 9 degrees off from the lows of the other two forecasting services. Other than the windchill, the three forecasts' highs and lows are within a couple of degrees difference. This would be normal as the calculations with the forecasting formulas will differ based on information on hand at the time.
Weather Forecasting began with early civilizations monitoring meteorologic and astronomical events to monitor changes in the weather based on the season. Babylonians began trying to predict short term weather around 650 B.C. based on the appearance of clouds and 'halos' (No, they weren't playing video games, they looked at circles of light surrounding an object; in this case, usually the Sun and the Moon). People tried to predict the short term weather using their experiences and folklore up until the end of the Renaissance, when it became evident that these methods were inadequate, and that to accurately predict short term weather, they needed to increase their knowledge of the weather. After that, they continued to refine their instruments and methods for forecasting the weather while observations and technology increased for the atmosphere. (Want a deeper summary? Me neither, but here it is anyways)
Now I'll discuss some weather lore. The first, probably everyone has heard: "Red sky at night, sailor's delight, Red sky at morning, sailors take warning." This saying observed that when the sunset was red, there would be dry weather the next day; and that when the sunrise was red there would be bad weather that morning. The second saying is just a myth and actually doesn't have any scientific evidence to prove it. It is: "Cats and dogs eat grass before a rain.". While some observations can of nature can sometimes predict the weather, this is not one of them. Cats and dogs normally eat grass, as they require some vegetation for their health. If you want, you can look on Wikipedia for the scientific explanations for these sayings. (I know Wikipedia isn't allowed as a school resource, but that article is actually very interesting)
Hey, Luke T here. Found out that I was supposed to be blogging about the weather for my Science a week before it ended. Yeah. My fault though, didn't even start work on the course till I was supposed to be three months through it. Ooopsy.