weather and climate 3

weather and climate 3 - weather3 18:23...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
weather3 18:23 Lecture 11/23/11 (origination of cyclones) Learning Objectives     1. Identify locations where cyclones originate. 2. Explain how the surface flow can affect the development of the upper-level  flow (temperature advection!) 3. Explain how the upper-level flow can affect the development of the surface  flow (upper level convergence / divergence!) “vertically stacked” cyclone: low pressure aloft is directly above low pressure at the  surface 1. surface convergence accumulation of mass low pressure disappears 2. surface divergence loss of mass high pressure disappears 3. we do need other conditions for cyclogenesis 4. note: in extratropics, vertical stacking typically means that a cyclone will decay divergence aloft (above a low) 1. loss of mass (above a low) 2. low pressure DEEPENS direction of wind affects CF and PGF balance 1. upstream of trough: flow is in geostrophic balance—PGF and CF balance 2. middle of trough axis: air is curving to the left (relative to flow) 1. CF is weaker than PGF winds are slower 3. Downstream of trough: flow is not curving. It is in geostrophic balance again Upstream of trough: air is “piling up” or converging Downstream of trough: air is “spreading out”, or divergin
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Air tends to CONVERGE upstream of trough and DIVERGE downstream of a trough Consider: upper level trough that’s situated to the west of a surface low 1. Divergence aloft above surface low 2. Convergence aloft above surface high If divergence aloft > surface convergence: loss of mass, low intensifies If convergence aloft > surface divergence: accumulation of mass, high intensifies Lecture 12/2/1011 (ocean circulation) Thermohaline circulation : water sinks in the north Atlantic and Antarctic, fills the  deep ocean around the globe 1. Returns to surface in Indian, pacific, and southern oceans, and returns to the  Atlantic Thermo : warm water loses heat as it moves N. in the Atlantic Haline : evaporation causes water to become more salty as it moves north Thermohaline :   water is more dense as it moves toward the north Atlantic Hadley circulation + coriolis force easterly trade winds SST : warm in W. Pac; “cold tongue” in E. Pac Force balance for water in the equatorial pacific: 1. Wind pushes water westward (wind stress) 2. CF balances wind stress 3. Water DIVERGES at the equator Thermocline : large vertical temp. Gradient that separates warm surface water from  colder, denser sub-surface water 1. Note: thermocline slopes upward toward east
Background image of page 2
The cold tongue 1. Why is there a cold tongue? 1.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

weather and climate 3 - weather3 18:23...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online