How do surface features influence local wind patterns?
Mountains, hills and tall buildings act as windbreaks. They also cause clouds to lift over them which means clouds that are saturated will have to lose some moisture to clear the obstacle. This may cause cooling which decreases the amount of lift. This generally causes a change in air pressure. Remember, high and low pressure areas play a part of how fast air moves into an area. Heat islands, caused by the way cities are constructed will also play a part, as will naturally occurring heat spots, such as volcanoes or even large bodies of water. Obstructions either block or deflect wind, low pressure areas draw wind.
3 blades?The more blades there are on a wind turbine, the higher will be the torque (the force that creates rotation) and the slower the rotational speed (because of the increased drag caused by wind flow resistance). But turbines used for generating electricity need to operate at high speeds, and actually don't need much torque. So, the fewer the number of blades, the better suited the system is for producing power.Did you know? About 90% of the installed wind turbines today have three rotor blades.Theoretically, a one-bladed turbine is the most aerodynamically efficient configuration. However, it is not very practical because of stability problems. Turbines with two blades offer the next best design, but are affected by a wobbling phenomenon similar to gyroscopic precession.Since a wind turbine must always face into the wind, the blades will have to change their direction vertically when there is a shift in wind direction. This is referred to as yawing. In the case of a two-bladed system, when the blades are vertical (i.e., in line with the tower and the axis of rotation) there is very little resistance to the yawing motion.But when the two blades are in the horizontal position, the blades span a greater distance from the axis of rotation and so experience maximum resistance to yawing (notice how a spinning figure skater slows down when they bring their arms away from their body. As a result, the yawing motion starts and stops twice per revolution, and this leads to stress on the turbine due to blade chattering.On the other hand, a turbine with three blades has very little vibration or chatter. This is because when one blade is in the horizontal position, its resistance to the yaw force is counter-balanced by the two other blades. So, a three-bladed turbine represents the best combination of high rotational speed and minimum stress.Learn More engrjaffarkhan@gmail.comCanadian Wind Industry Association: http://www.canwea.ca/Gyroscopic Precession: www.gyroscopes.org/behaviour.aspThe role of arms in figure skating: http://www.bsharp.org/physics/st...
What are the two main variables of water erosion?
Water erosion is due to dispersive and transporting power of water. Factors affecting are: 1. Climatic factors: This includes rainfall characteristics, atmospheric temperature and wind velocity 2. Soil characteristic: This affect infiltration rate of soil, Infiltration rate depends upon permeability of soil, surface condition and presence of moisture in it. 3. Vegetation: It creates the obstacle for raindrops as well as glowing runoff. A good vegetative cover completely reduces the effect of rainfall on soil erosion. 4. Topographic effect: The land slope, length of slope and shape of slope are main factors which influences soil erosion. As slope of land increases from mild to steep, erosion increases
Which way to the winds blow over costa rica?
Hi, Most of the time the prevailing wind comes from the Caribbean (east). That is where we get most of our weather patterns from. It is not true that the globally the winds always run west-to-east. There are many weather patterns that affect different parts of the globe in different ways. For example, it is true that most storm patters travel west to east in the US, but what about Nor'easters in New England? Or how about Hurricane Katrina, did it come from California? Carlos
What three factors affect the amount of air resistance on an object?
factors are below. There are 5 factors, plus drag coefficient includes a few more. wikipedia: The drag equation calculates the force experienced by an object moving through a fluid at relatively large velocity (i.e. high Reynolds number, Re > ~1000), also called quadratic drag. The equation is attributed to Lord Rayleigh, who originally used L2 in place of A (L being some length). The force on a moving object due to a fluid is: Fd = (1/2)pv²ACdV where Fd is the force of drag, p is the density of the fluid (Note that for the Earth's atmosphere, the density can be found using the barometric formula. It is 1.293 kg/m3 at 0 °C and 1 atmosphere.), v is the speed of the object relative to the fluid, A is the reference area, Cd is the drag coefficient (a dimensionless parameter, e.g. 0.25 to 0.45 for a car), and V is the unit vector indicating the direction of the velocity (the negative sign indicating the drag is opposite to that of velocity). The reference area A is often defined as the area of the orthographic projection of the object — on a plane perpendicular to the direction of motion — e.g. for objects with a simple shape, such as a sphere, this is the cross sectional area. Sometimes different reference areas are given for the same object in which case a drag coefficient corresponding to each of these different areas must be given. In case of a wing, comparison of the drag to the lift force is easiest when the reference areas are the same, since then the ratio of drag to lift force is just the ratio of drag to lift coefficient. Therefore, the reference for a wing often is the planform (or wing) area rather than the frontal area. For an object with a smooth surface, and non-fixed separation points — like a sphere or circular cylinder — the drag coefficient may vary with Reynolds number Re, even up to very high values (Re of the order 107). For an object with well-defined fixed separation points, like a circular disk with its plane normal to the flow direction, the drag coefficient is constant for Re > 3,500. Further the drag coefficient Cd is, in general, a function of the orientation of the flow with respect to the object (apart from symmetrical objects like a sphere).
Jet Streams and Indian MonsoonsThe jet streams are high altitude (9000-12000 m) Westerly winds between middle latitudes (summer 35°N, winter 20°N-35°N) in the Northern hemisphere. Recent researches have shown that these winds exert considerable impact on surface weather conditions. The tropical Easterly jet stream extends far to the North of Tibet of the Tibet and the air flow is roughly along the Kolkata- Bangalore axis. These upper air Easterlies descend into the permanent high pressure area formed over the southern Indian Ocean, This naturally intensifies the high pressure already present there.It is a form this high pressure cell that the onshore winds start blowing towards the thermally induced low pressure area, developed in the Northern part of the Indian sub-continent. After crossing the equator such winds become South-Westerly and are known as the South-Westerly Summer Monsoons.These surface winds have vast potentiality for South-Westerly summer, monsoon and precipitation. It is therefore, clear that the strength of the Easterly jet stream is directly related to the intensification of permanent high formed over Southern Indian Ocean. Since this high pressure makes the pressure gradient steeper, so it is the main causative factor for determining the vigour of the summer monsoon.