# Talk:Bulk Richardson number

Active discussions
WikiProject Weather (Rated Stub-class, Low-importance)

## Major update and revision

I added quite a bit of content pertaining to BRN and storm-type forecasting as part of a mesoscale meteorology class assignment. For BRN, as defined by the AMS, supercell development is usually linked to BRN values between 10 and 45 not 50 to 100 as was previously stated.

The content here is only regarding the BRN reported in soundings and is used for storm-type forecasting. I do not intend to say anything relating the BRN for calculating planetary boundary layer (PBL) height as the BRN is defined differently there (as I understand it, height thickness isn't fixed in that case since height is the dependent variable). Again, the content I have added only pertains to BRN as used and calculated for mesoscale forecasting.

Please discuss any problems with the content here before obliterating or significantly altering my contributions. I can back up what I have stated here. Thanks.

--Kerm23 19:21, 24 April 2007 (UTC)

## Omissions

The calculation for BRN here does not give any info on units. Also from my understanding, it is not the 6 km wind that is used but a 0-6 km density-weighted mean wind. The references either have omissions or obfuscate the definition with extremely detailed content. I have tagged this as needing attention by an expert. -Rolypolyman 16:22, 15 October 2007 (UTC)

## Units

The BRN defined here is a dimensionless quantity. CAPE has units of J/kg = m^2/s^2. The denominator is the difference between two wind speeds, so the units there are m^2/s^2, so the units cancel out appropriately. Again, this is a simple metric commonly used to predict mesoscale convective potential. If you think about it, the denominator is a simple approximate integration of the wind speed over the two height levels.

--Kerm23 —Preceding unsigned comment added by 155.101.17.78 (talk) 20:48, 22 January 2008 (UTC)

## Formula

Hi, I noticed there was no formula for the Bulk Richardson Number in this article. I've recently been part of a group updating the article on Cold air damming and we are linking to Bulk Richardson Number. We've been using Gary Lackmann's Midlatitude Synoptic Meteorology: Dynamics, Analysis, and Forecasting as a source for a lot of our information, and we used the Bulk Richardson Number formula from his chapter on Cold air damming.
Here's the formula we included in Cold air damming coded in LaTeX
${\displaystyle Ri={\frac {g\Delta \theta _{v}/\theta _{v}}{[(\Delta U)^{2}+(\Delta V)^{2}]/\Delta Z}}}$

I hope this is somehow helpful. I'm not a meteorology expert, so I didn't add it to the article, but I'll get someone to take a look and make sure this is correct.

Nebelmeister (talk) 18:21, 9 October 2013 (UTC)

I checked with someone more familiar with this information than me, and they said this is the correct formula, so I'm going to add it to the article. Nebelmeister (talk) 20:24, 9 October 2013 (UTC)