What causes a "lake effect" in weather conditions.  I live in Rochester, N.Y.?
481986
The effect of any lake, especially the Great Lakes, in modifying the weather in nearby areas.\n\nLake effect snow is produced in the winter when cold winds move across long expanses of warmer lake water, picking up water vapor which freezes and is deposited on the lee shores. This effect is enhanced when the moving air mass is uplifted by the orographic effect of higher elevations on the downwind shores. This uplifting can produce narrow, but very intense bands of precipitation, which deposit at a rate of many inches of snow per hour. The areas affected by lake effect snow are called snowbelts.\n \nLake effect snow produced as cold winds blow clouds over warm waters\n\nCold winds in the winter typically prevail from the northwest in the Great Lakes region, producing the most dramatic lake effect snow falls on the East to south shores of the Great Lakes. This lake effect produces a significant difference between the snow fall on the eastern and western shores of the Great Lakes. If the air temperature is not low enough to keep the precipitation frozen, it falls as lake effect rain. Lake effect snows at the Tug Hill Plateau on the southeastern side of Lake Ontario frequently set the daily records for snowfall in the United States. Lake Erie also produces a similar effect for a zone stretching from the eastern suburbs of Cleveland to Buffalo, but Lake Erie often freezes due to its shallowness, and ice cover stops the lake effect. In order for Lake Effect rain or Snow to form the temperature difference between the water and the air at 1500 meters above the surface must be at least 13 degrees C. The southern and southeastern sides of the Great Salt Lake also receive significant lake effect snow, but it is much more severe over the Great Lakes.\n\nOne area that receives the most lake effect snow is the snow belt in the Upper Peninsula (UP) of Michigan, near the cities of Houghton, Marquette, and Munising. These areas frequently average over 200 inches, and may receive close to 300 inches of snow a year (for comparison, on the western shore, Duluth, Minnesota receives only 77 inches). Due to the low populations of these areas, they do not get the publicity of the lake effect snows affecting Buffalo, Erie, Cleveland, or Upstate New York. Lake Superior and Lake Huron rarely freeze due to their size and depth; lake effect snow can fall continually in the UP and the Ontario, Canada snowbelts during the winter months. The most famous lake effect storm was the Blizzard of 1977, which struck the Buffalo area from January 28-February 1, 1977. It was the first instance of a region of the United States being declared a Federal Disaster Area because of excessive snowfall. Cities such as Toronto, Hamilton, Detroit and Chicago frequently miss out on lake effect events because they are not on the leeward shore of a lake during a Northwest oriented wind (wind coming from the Northwest, heading to the Southeast). However Toronto and Hamilton are often close enough to Georgian Bay and Lake Huron that they receive small amounts of Lake Effect Snow each winter.\n\nLake effect of extremely cold air over still warm water in early winter can produce thundersnow, snow showers accompanied by lightning and thunder.\n\nEven when precipitation is not produced, any time cold air passes over warmer water it produces cloud cover. Fast moving cold fronts, known as Alberta clippers often cross the Great Lakes. After the passage of a cold front, winds tend to switch to northwest, and a frequent pattern is for a long lasting low to form over the Canadian Maritimes which may pull cold northwestern air across the Great Lakes for a week or more. Since the prevailing winter winds tend to be colder than the water for much of the winter, the southeastern shores of the lakes are almost constantly overcast, leading to the use of the term The Great Gray Funk as a synonym for winter. These areas have a high rate of seasonal affective disorder, a type of psychological depressio
76119
Have you ever looked down the street on a hot day and see that the street and air look blurry?  The same thing is happening.  \nWhen air is heated and cooled, its angle of defraction is changed.  When the angle is changed from the city lights, sometimes the light will be angled so that it misses your eyeball.\nWhen the road is hot, the angle of defraction is changed and gives the wavy appearance.
861405
New York City's water comes from lakes in the mountains of upstate New York.  It is held in resevoirs (such as the Croton Reservoir) north of the city and transported throughout the city via a tunnel system.
818992
Cool - you seem to have really interesting weather.\n\nYes, if there is a 1000 foot difference between you & the town 7 miles away you will certainly experience different weather in some situations - and typing in your zip code for an online forecast generally will not help - to my knowledge the type of meso and micro scale effects you mention are not included in any of them. You really have to learn how your local weather differs from that at surrounding areas (which are forecast for) for specific situations.\n\nFor example, when the temperature is near the dewpoint with storm systems affecting your region, the cloud base in town can be below 1000 feet and below you. There are many orographic effects on the microscale - mountain-valley breezes, and the extra elevation can in certain situations cause showers to occur over you but not them. After a cool & clear night, you may become warm quicker than the town does - cool air persisting in the valleys longer after sunrise - then they'll become quite a bit warmer than you during afternoon.\n\nThough the NWS attempted to place the doppler radars at locations for the best overall coverage, some mountain locations still cause problems. The base reflectivity images you typically see when you look at a "radar map" are obtained using a beam tilted .5° above horizontal. If the precipitation is occurring primarily below that or there is an intervening mountain, you may get a small or no signal. That is much more common with snow rather than rain showers because low & rather thin clouds can sometimes produce them. Raindrops generally need a much greater vertical distance for the water droplets to combine and become large enough to fall out of the cloud. Ice crystals can float around horizontally much more and do that.\n\nSo there are many possibilities, but I would have to know exactly where you are to say anything specific.\n\nI saw something cool visiting Clingman's Dome in Tennessee one September. It was a sunny day, but on the road to the summit there was a large low area in amongst the mountains over which a cumulus cloud had formed. Became cloudy for a few minutes as we passed by then was sunny again. On the way back down a few hours later, the cloud was still there. There were a few small cumulus clouds here & threre occasionally, but some orographic circulation evidently caused that cloud to form & persist much of the day. Was a warm day - I am guessing a little over 80° even at the summit.
248222
Depends on where you are. If you live near a body of water, the wind shifts from day to night because of the nature of wind. Air will move from higher pressure to lower, and in the day, the water is colder than the land, so the wind will run to the water. In the night, the water is warmer than the land, so the wind will rush inland. In general, I'd say in the morning, because the sun's rays would heat things up faster, causing higher air pressure, and resulting in wind flow.
1044121
I can say the same about the weather here in NS Canada!! We've had about 2 weeks of rain!! We didn't get the deluge that the Eastern seaboard States received as they had extreme flooding in areas!! \n\nMy front lawn is one squishy mess and we had to cut ditches in the yard to drain off the excess water away from the house. We actually have had 2 days of sun! It's nice to be able to go outside and not be stuck in the house!!
42166
I vote for Lake Erie. It causes the most snow. The fact that it is a long east-west running lake, and its depth cause this. Of course, all the Great Lakes produce lake effect snow, but Erie is deeper than Lake Ontario, and the effected city (Buffalo) is larger than other cities that get hit by lake effect snow from the other lakes (Watertown—Lake Ontario, Kalamazoo—Lake Michigan, and others). Having grown up just south of Buffalo, I can attest to the devastation of blizzards from lake effect snow. This was especially so on Jan. 29, 1977, when the infamous “Blizzard of ’77” hit.
1042343
Lakes don't hold water... \nLakes happen because the water coming into the lakes through streams, springs, rivers and run-off is in balance with the amount of water being lost from the lake as rivers further downstream, seepage through the ground and evaporation of vapour into the air.\nYou dig a hole in the ground and fill it up, it will lose the water as it drains away, but if you put a hose into it with a steady supply of water, the water appears as if it is not going anywhere.. VOILA.. you have built a lake!!!\n\nAnd.. BY THE WAY.. WEIRD DUDE.. really.. go get a life.. This person asked a fair question and deserved a fair answer..
825004
Probably just the weather changing quickly ? We had a thunderstorm a few weeks ago, except it was snowing with it. Really warm before it and really cold afterwards... I'm sure it's nothing to alarm yourself over.
288151
Temps close to the freezing point. If you have noticed often when rain is changing to snow quickly,the flakes at times are huge!
18597
To save you some time, here is a great description in plain English:\n\nIt all begins when bitter cold air dives across the Great Lakes. As the cold air flows over the warm water, the relatively warm lake water heats the air's bottom layer as lake moisture evaporates into the cold air.\n\nSince warm air is lighter - less dense - than cold air, the heated air rises and begins to cool.\n\nAs the air cools, the moisture that evaporated into it condenses and forms clouds, and snow begins falling from the cloud if the air is humid enough.\n\nThe wind pushes the clouds over the land. As this happens, friction with the ground, which is greater than the friction between the lake's water and the moving air, slows the winds. This causes the air that's carrying the clouds to "pile up" - meteorologists call this "convergence."\n\nConvergence increases the amount of snow that's falling on the land compared with the amount falling on the lake.\n\nAs the wind continues inland it runs into hills, sometimes only a few miles from the lake, which forces the air to rise, which cools it. As the air cools, more humidity condenses to create even more snow. This is why the heaviest lake effect snow falls on hills inland from the great lakes. \n\nThe source also has an outstanding graphic depiction and explanation.
545928
Yes, I have seen that happen for years. Sycamore especially. The wind blows them in a twist. I don't know the involvement with the water, but when it rained it usually blows first and that's when you see the leaves twist over...
1027903
I'm not completely sure, but I do know that the ring signals that the next day will be rainy. Perhaps it has something to do with an incoming front. Or a rise in humidity.
725902
Hi. They are surface currents. : http://www.answers.com/topic/mixed-layer
648606
Usually,this is due to irrigation- When I was a boy, I never saw that occur until we got irrigation- and then it was on still, humid days with a rapid drop in temp at night- The moisture that is on the fields, which is much higher than that in the surrounding area, evaporates to a higher degree (obviously, because there is more water) but stays close to the field because of the stillness of the air- then, when the temp drops, the air becomes super-saturated with water, and voila, fog.
853975
I can say that they should be heading your way soon.  It finally got cold here today and will stay that way.  Lakes and ponds are staring to freeze over.  I saw some geese and a couple large flocks of mallards moving south this evening.  Good hunting.
1033408
it is here in newyork right now! but you should maybe check the local weather channel, or website i hope you have a beautiful day!