Turbulence is classified by its intensity ranging from light to extreme. We have already discussed Turbulence and CAT in lesson 10. In aviation, it refers to bumpines in flight. TURBULENCE - Any irregular or disturbed flow in the atmosphere. If the cooling is strong enough, a nocturnal inversion results. We know with radiational cooling, the ground will cool faster than the overlying airmass. Airmass wind shear - This type of wind shear ocurrs at night under fair weather conditions in the absence of strong fronts and/or strong surface pressure gradients.Since cold air is denser than warm air, it will always wedge under the warm air, creating a sloping frontal zone that contains horizontal and vertical shear. Fronts and shallow lows - Remember that a front is a boundary between two air masses.The average outflow speed is about 25 knots. Once it reaches the ground, the lifetime of a microburst ranges from 5 to 30 minutes. As the air spreads out horizontally, it forms a vortex ring which rolls upward along its outer boundary.

Microbursts have a strong core of cool, dense air descending from the base of a convective cloud.

Microbursts - A concentrated, severe downdraft that induces an outward burst of damaging winds at the ground with a horizontal dimensions of 2.2 nautical miles (4 km) or less.

It is important to understand some of thse main sources of wind shear. Wind shear may be associated with a thunderstorm, a low-level temperature inversion, a jet stream or a frontal zone.

Vertical wind shear - A change in the wind over a vertical differene.

Horizontal wind shear - A change in the wind over a horizontal distance.

Wind shear can be broken up into two parts: We can think of wind shear as a gradient in wind velocity that can be interpreted in the same way as a pressure or temperature gradient. WIND SHEAR is a change in wind direction and/or speed with height over a very short distance. Should already know some basic knowledge about turbulence from last week. If someone were to head for the lake and wander around a bit, he would expect to see some deer.This week's background information is available in Chapters In this case, the speaker is communicating that the deer aren't at the lake, but close enough for the lake to be a landmark. There's an awful lot of deer around about that lake.

If we take that usage and apply it to a region, as in your example, we can understand how someone might use it to mean 'vicinity'. This phrasing is kind of rural, and indicates someone who is very casual and 'laid-back'. Here the speaker has taken the already imprecise 'about 7:30' and added an additional word meaning the estimate is not precise. Here the speaker has explicitly said that they will arrive near to 7:30, rather than at 7:30 'on the dot'. The speaker is either very certain that they can arrive, or believes that they will be forgiven for being off by a few minutes. This means exactly 7:30, with no margin for error. The phrase 'around about' indicates something that is somewhat close, with a significant margin for error. It sounds like you are trying to use 'around about', which is often shortened by a rural dialect to sound like 'roundabout'.

Your use of roundabout to mean an area almost fits the first definition - if you took a roundabout path to a destination then you would travel through much of the surrounding area, but in a very imprecise way. (Alternately, a roundabout can mean a traffic circle, a type of intersection where cars flow counterclockwise rather than crossing paths.) She admitted she was busy, and complained about her disappointing date.' 'I knew she would be suspicious if I asked her about her date directly, so instead I took a roundabout approach and asked if she saw last night's game. A native speaker would understand roundabout to mean indirect. Your definition for roundabout is not typical. 'All police cars in the vicinity of 45th Street and Main please respond' would be understood to be several miles, while 'There were two witnesses in the vicinity of the crime' would mean close enough to see what happened. Second, vicinity is not a specific distance, but refers to a region that is understood by the speaker and listener. First, vicinity is very formal, and often used in official reports, so it may seem unusual in casual conversation. I would suggest two things to keep in mind when using it.

Thunder in the vicinity meaning