Winds “Aloft”Point of Reference:FrictionCyclones and AnticyclonesLow Central Pressure:High Central PressurePressure and Winds on a Smooth, Uniform EarthDuring EquinoxNOTEGEO 155 1st Edition Lecture 6Outline of Last Lecture I. Global Energy BalanceOutline of Current Lecture I. Atmospheric Forces and Motiona. Gradient Winds Alofb. Friction and Surface Windsc. Cyclones and AnticyclonesII. General Circulation of the Atmospherea. Pressure and Winds on a Smooth, Uniform Earthi. At Low LatitudesCurrent LectureAtmospheric Forces and MotionWinds “Alof”- In the Northern Hemisphere – Coriolis deflects wind so far to the right that moves parallel to isobarso Wind moves very fast due to the Coriolis Effecto Known as “gradient wind” or “geostrophic wind” Here, pressure gradient force moves from high to low pressurePoint of Reference: When determining the direction of Coriolis, always remember that your point of reference is standing with your back facing towards the wind- That is, in a gradient wind, the pressure gradient force moves from high pressure to low pressure. Thus, one would stand with his or her back facing toward the high pressure gradient so that Coriolis would deflect wind to the right (in the Northern Hemisphere).Friction- Due to friction at the Earth’s surface, winds move slower closer to the surfaceo Winds are not deflected as strongly near the surface as compared to geostrophic windThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Rather than being deflected parallel to the isobars, wind deflects at an acute angle to the isobars- In the Northern Hemisphere, winds deflect to the right when facing away from the windCyclones and AnticyclonesLow Central Pressure:- Cyclonic circulation- Winds spiral into the low pressure center- In the Northern Hemisphere – Coriolis deflects the wind to the right at an acute angle in all directions of the pressure gradient force (which pushes inward from high to low pressure)- In the Southern Hemisphere – Coriolis deflects the wind to the lef at an acute angle in all directions of the pressure gradient force (which lies perpendicular to the low pressurecenter in four directions)High Central Pressure- Anti-cyclonic circulation - Pressure gradient force pushes outward- In the Northern Hemisphere – wind blows right- In the Southern Hemisphere – wind blows lefGeneral Circulation of the AtmospherePressure and Winds on a Smooth, Uniform EarthDuring Equinox- Equator receives most solar radiation due to solar beamingo Air heats up and rises Atmospheric pressure decreases – “equatorial low pressure” Air reaches tropopause, then moves back to the surfaceo Also known as the Inter-tropical Convergence Zone (ITCZ) and the “Doldrums”, where winds converge from the subtropics and blow horizontally- Air reaches surface again at higher latitudes – 30 degrees north and south of the equator(“Horse Latitudes”)o “Sub-tropic High Pressure”(STH) – creates a pressure gradient force Wind deflected towards equator from high pressure areasNOTEWinds are always named afer the direction in which they flow from- Winds from STH known as “Easterly Trade Winds” o Northeasterly Wind – winds from 30 degrees Northo Southeasterly Wind – winds from 30 degrees South- Air sinks back to the equatoro Hadley cells – vertical cross section of the atmospheric pressure changes Air rises, moves to sub-tropic highs, sinks back to surface, and returns to
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