建國中學

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斜溫圖

Presenter: 122527 Brine

Index

Introduction

Things to know

Basics of skew-T

How to use skew-T

INtroduction

commonly used thermodynamic diagrams

general purposed ones

  • P-V diagram
  • T-S(specific entropy) diagram
  • H(enthalpy)-S diagram
  • Psychrometrics chart
  • cooling curve

You guys are smart and know these already right?

weather bois

  • Emagram
  • Stüve diagram
  • Tephigram
  • Skew T Log P diagram

weather bois

  • Emagram
  • Stüve diagram
  • Tephigram
  • Skew T Log P diagram

Emagram

  • Devised by Heinrich Hertz
  • P-T diagram based
  • European
  • First of the kind

Stüve diagram

Tephigram

  • T-S(phi) based

 

I don't actually know

SKew T

  • We'll talk about this later

"Preview"

things to know

what you will need to understand the following(maybe not)

Physical quantities - bar

1\ bar = 100,000\ Pa \leftrightarrow 1\ mb = 1\ hPa

why switch?

SI\ units \rightarrow 1\ Pa = 1\frac{N}{m}

Entropy

\Delta S = \frac{\Delta Q}{T}
a\ reversible\ process\ should\ have\ an\ entropy\ of\ 0
"possibility"

First law of thermodynamics

\Delta Q = \Delta U + W
dH = TdS + vdp

Potential Temperature

how?

Potential Temperature

  • We move air parcels to a certain height to compare their temperature at such altitude
\theta = T_0(\frac{P_r}{P_0})^\frac{R_d}{C_p}
\frac{\partial \theta}{\partial z} > 0

Basics of Skew-T

Introduction to what made me suffered

What a skew-T looks like

base element

log where

Back to the graph

Adiabats

Saturation mixing ratio

Review

Before jumping into application

full picture

IsoBars

Isotherms

adiabats

Saturation ratio

Other given info

The rest of the things that make this even more messy

Wind

Dewpoint and temperature

what's\ this

Dewpoint and temperature

what's\ this

The rest of the info

  • this is too much.

The rest of the info

  • this is too much.

Condensation

that's\ a\ lot\ of\ names!

Lifting condensation level

 level an air parcel would need to be raised to to become saturated

convective condensation level

 a parcel, if heated to the “convective temperature,” would freely rise and form a cumulus cloud

LeVel of free condensation

self-explanatory

Equilibrium level

It's time to stop.

CAPE

Convective Available Potential Energy

V_{max} = \sqrt{2CAPE}
1500,\ 2500

Convective Inhibition

\sout{cout}\ cin

Quantitative precipitation forecast

yes.

INdices

Some other tools to make forecasts

Total totals index

  • yes
VT = T_{850 mb} - T_{500 mb}
CT = T_{dew\ 850 mb} - T_{500 mb}
TT = VT + CT
45,\ 50,\ 55(K)

K Index

K = T_{850 mb} + T_{dew\ 850 mb} - T_{500 mb}\\ - (T_{700mb} - T_{dew\ 700 mb})

around 30(K) $$\downarrow$$ less rain possibility

LIFTED Index

LI=T_{500 mb\ env} - T_{500 mb\ parcel}
-3,\ -6,\ -9

Showalter index

  • I am not actually sure how this is calculated
SI=T_{500 mb\ env} - T_{850\rightarrow 500 mb\ parcel}
-3,\ -4,\ -6

SWEAT

  • Severe WEAther Threat Index
  • The fomula is too complicated
  • It's meaningless to remember / know at this point
150,\ 300,\ 400

that's the end of introduction

  • or is it?
  • there are actually plenty more of them
  • our brain is going to explode

How to use Skew-T

This is an important skill, I suppose.

Use the pre-calculated info

so\ simple!

some skew-ts

SOME SKEW-TS

Some Skew-Ts

taiwan's skew t

8\ a.m.,\ 8\ p.m.
0:00\ UTC,\ 12:00\ UTC

That's IT

Thank you for listening.

斜溫圖 Skew-T Log-P Diagram

By Brine

Source: BrineTaiwan

斜溫圖 Skew-T Log-P Diagram

A skew-T log-P diagram is one of four thermodynamic diagrams commonly used in weather analysis and forecasting.

  • 248

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