Download presentation

Presentation is loading. Please wait.

1
1. The horizontal equations of motion: smaller-scale motion 2. The vertical equation of motion 3. The thermal wind ATOC 4720 class34

2
H L Northern Hemisphere (NH): P1 P2 P3 P4 P5 x y PGF CF Previous class: GEOSTROPHY:

3
Geostrophic wind value:

4
In PBL, friction is important. Frictional convergence toward the low pressure! Important! V cross the isobars!

5
Cross-isobar flow due to friction

6
The gradient wind

7
x y z 1.Smaller-scale convection : GEOSTROPHY BREAKS DOWN Observations for small-scale convection: Velocity U-V: 20 m/s; Time T (100-1000s)= S

8
Acceleration term: Coriolis term: Therefore, the Coriolis term can be NEGLECTED! Geostrophy breaks down! 0

9
2. The vertical equation of motion In z direction: Newton’s second law of motion for unit mass: negligible Free atmosphere negligible Large-scale motion, T: 1day; W:10m/s: Even for T=1000s,

10
Hydrostatic balance Hydrostatic balance is well satisfied even by mesoscale convection. Exercise: find out for what scale convection (vertical velocity and timescale), hydrostatic balance can break down.

11
3. Thermal wind relation Geostrophic wind speed: Perform vertical derivation: Between 2 layers:

12
Substitude (Z2-Z1) from the hypsometric equation (2.29) (for dry air)

Similar presentations

© 2021 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google