Radiosonde
Sounding Analyzer
A complete guide to using the sounding analyzer and understanding the thermodynamic pipeline behind it — from Wyoming archive fetch through CAPE integration, hodograph computation, and Skew-T rendering.
01 What Is a Radiosonde Sounding?
A radiosonde is an instrument package carried aloft by a weather balloon. As it ascends from the surface to the stratosphere — typically reaching 30 km altitude before the balloon bursts — it transmits temperature, humidity, pressure, and wind measurements at hundreds of pressure levels. This vertical snapshot of the atmosphere is called a sounding.
Soundings are launched twice daily at thousands of stations worldwide, at 00Z and 12Z UTC. The data are archived and publicly served by the University of Wyoming Upper Air archive at weather.uwyo.edu.
- Pressure (hPa): The vertical coordinate. Surface is near 1013 hPa; the tropopause is near 200 hPa.
- Temperature (°C): Measured by the radiosonde thermistor.
- Dewpoint (°C): The temperature to which air must be cooled at constant pressure to reach saturation.
- Wind direction and speed (°, kt): Derived from GPS tracking of the balloon's horizontal drift.
- Height (m): Geometric altitude above mean sea level.
02 What Does This Tool Do?
The Radiosonde Sounding Analyzer fetches a sounding from the Wyoming archive, parses the raw HTML response, computes a suite of thermodynamic stability indices, and presents the results through five output panels and a Skew-T diagram.
03 Using the Interface
Enter a WMO station number, date, hour (00Z or 12Z), and region, then click Analyze Sounding.
04 Reading the Outputs
CAPE (J/kg) — Convective Available Potential Energy. Rough thresholds: 0–500 weak, 500–1500 moderate, 1500–3000 large, >3000 extreme.
CIN (J/kg) — Convective Inhibition. Negative by convention.
Lifted Index — Temperature difference between environment and lifted parcel at 500 hPa. Negative values indicate instability.
05 The Skew-T Log-P Diagram
The Skew-T is the standard atmospheric sounding diagram. The vertical axis is the logarithm of pressure. The horizontal axis is temperature, skewed to the right with increasing altitude.
- Blue — Temperature profile.
- Green — Dewpoint profile.
- Red dashed — Lifted parcel trace.
06 Parameter Space Examples
Station 72357 (Norman, OK) provides excellent examples of quiescent midwinter, pre-convective spring, and post-frontal stable soundings.
07 Pipeline Architecture
The application is a single Go binary. All computation is in-process. The pipeline: SoundingRequest → wyoming_fetcher → wyoming_parser → analyzer → hodograph → exporters → HTTP response.
08 Wyoming Data Fetch
The Wyoming archive serves soundings as HTML pages via a CGI endpoint. URL format: https://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT:LIST&YEAR=...&MONTH=...&FROM=...&TO=...&STNM=...
09 HTML Parsing
The Wyoming archive returns raw HTML. The parser uses string search on the raw byte buffer to extract two <pre> blocks: the sounding data table and the station metadata/indices block.
10 Thermodynamic Engine
All thermodynamic functions follow Bolton (1980). Saturation vapor pressure: es(T) = 6.112 · exp(17.67 · T / (T + 243.5)) hPa.
11 Parcel Lifting & CAPE Integration
The parcel is lifted dry adiabatically below the LCL and moist adiabatically above. CAPE and CIN are integrated using the trapezoidal rule in log-pressure coordinates.
12 Hodograph & Wind Shear
Wind vectors are decomposed into u/v components using meteorological convention. Bulk shear and Bunkers right-mover storm motion are computed from the hodograph.
13 Export & NaN Handling
All missing values are represented as math.NaN() internally. Before JSON marshalling, NaN is replaced with -9999.0. The browser renders -9999 as "N/A".
14 API Reference
| Method | Path | Description |
|---|---|---|
GET | /api/analyze | Fetch, parse, analyze, return complete sounding JSON |
GET | / | Serve the single-page application |
GET | /docs/engineering_tutorial.html | Serve this tutorial |