TherMap 3.0

Released March 2017

Maps showing the expected thermal
hotspots of selected mountain regions

For ridge wind maps see WindMap

These maps have been calculated on the basis of the empirical model outlined in the model description below. Hundreds of validations with actual flight records have confirmed their validity.
A particular advantage of this approach is that the maps also show the thermal potential of less visited regions.

© The utilization of the maps for noncommercial purposes remains free. For commercial uses, quotations, as well for further publication, written
copyright permission must be obtained via the mail address mentioned at the end of this site.

Menu

Introduction

Using the Maps

Regions Available

Model

View/Download Maps

View with Google Earth

FAQ

Links/Contact

Introduction

Position the cursor on the above picture to see a TherMap of same region. TherMap is a tool for glider pilots, to visualize the local potential of thermals on digital maps on a given date and hour, assuming favorable meteorological conditions (sunshine, unstable atmosphere). For any sensible time and date of interest, such thermal hotspot maps can be downloaded from this site free of charge.

A second possibility is to directly overlay the maps on Google Earth, which offers further viewing facilities such as 3D perspectives. However according to our experience, this works so far only with Google Earth versions running on PCs.

Unlike other thermal maps, which are usually based on statistical analyses of flight records, the maps of TherMap have been derived solely from the orography ( cf. Model ). The maps therefore also show the potential of thermals in less known territory.

Before the flights TherMap maps permit to study the best itineraries, or to explain them to less experienced pilots, particularly across less known regions. After the flight, flight logs (typically IGC-files converted to KML for use with Google Earth) may be superimposed to these maps, to find out where more promising paths might have been followed.

What is new in TherMap 3.0 ?

One of the limitations of TherMap 2.0 was that the same filter limit for the thermal potential had been applied across the entire map. As a result, some areas with high thermal potentials remained too colored whereas the potentials of weaker locations were hardly displayed at all. In TherMap 3.0 filters have therefore been adapted to the local areas in order to reduce this undesirable effect and to make the underlying topography still more visible, as outlined in the model description. To best interpret the maps, it may however be necessary to use a slightly larger zoom level.

Secondly, since during the peak months the length of the day is longer, the reference hours of the morning and the evening maps have been shifted accordingly. This modification had actually been proposed by paraglider pilots.

Using the Maps

a. How to read the maps
b. Flight preparation
c. Reviewing flights
d. Limitations of TherMap approach

a. How to read the maps

Zooming: The maps should be zoomed at least to 100 percent. Original maps may contain about 10 Mb in JPG format, which corresponds to about 30 standard screens. The maps should be studied in detail, if necessary by zooming above 100 percent, due to their huge information content. For your convenience it is recommended to use viewers (e.g. MS Picture Manager®) permitting to maintain the zooming level and the selected window frame while paging between different downloaded images.

Color coding: The colors of the temperature and the irradiance maps vary from green to yellow and finally red. Assuming a glider with a minimum sinking rate of 0.5 m/sec the colors represent approximately the expected climbing rates shown on the following graph:

Green areas appear in relatively flat regions or at the end of the day, and may indicate how to best stretch a flight path,
whereas red colors are typical for mountain hotspots during the peak hours of the day

3D visualization: Using the Google link below, linking TherMap with Google Earth® takes only seconds, whereas importing them for instance in SeeYou® (as raster maps) is more complicated and takes several minutes. For flight reviews, which can facilitate the identification of alternative flight paths, several free conversion programs can be found on the Internet to convert IGC flight record files into KML files. Upon clicking on the converted files, these will open with Google Earth®.

b. Flight preparation

Meteorology: TherMap supposes a calculated solar irradiance and a non-stable atmosphere responding to temperature increases. It is therefore only usable on sunny days with good meteorological conditions, i.e. an unstable temperature gradient and a sufficiently high condensation base. In other words, TherMap is a complementary tool to meteorological forecasts, but can in no way replace these. It is up to each pilot to learn and determine, when the conditions are suitable to make use of TherMap. In case of predominant winds it may further be worthwhile to consult WindMap.
Checking planned flight paths: TherMap is best used before the flight to check the local conditions at the expected time of overflight (e.g. when to change to the other side of a valley) and to note possible alternatives in case of unexpected changes.
In-flight use of TherMap: Consulting a map during the flight must not interfere with the necessary observation of the flight space. Tests with mobile navigation devices, into which TherMap hotspots had been imported, have shown that this represents a risky distraction from flight observation, further aggravated by the poor readability of most displays. However even with better displays, the mobile tools should be designed to automatically show the hotspots valid at the actual time, to avoid manual file manipulations distracting the pilot.

c. Reviewing flights

This requires the flight tracks to be traced on the maps closest to the date and time of the flight. Besides identifying possible alternative flight paths, such analyses also help to better interpret TherMap. Due to the ease of activating the maps on Google Earth, the latter tool is preferable for such analyses, because it does not require importing (raster) maps into flight planning application. On the other hand, the latter tools offer the known additional features of these specialized tools.

If needed, the following links open guidelines for making such analyses either with SeeYou or Google Earth

Color coded thermal pressure map in 3D-view with vario-flighttrack
(reproduced using SeeYou© on the basis of an imported thermal pressure map)

d. Limitations of TherMap approach

Limitations of radar maps: Radar reflection signals are not perfectly precise when scanning altitudes (precision is about 5 meters). They are particularly unreliable when reflected by water or ice. This it why it is difficult to automatically identify lakes on the basis of radar scan data. In TherMap many lake outlines have therefore been imported separately, but these imports had to be limited, due to the manual effort involved, and hence not all lakes are displayed. Some ice covered surfaces appear blurred. Fortunately neither of these limitations seems to limit the use of the maps.
Wind drift: The further away the glider is from the ground , the more its flight path may be shifted by the wind drift. Such shifts can be visible on TherMap flight tracks on a windy day.
Borders of plains: Air heated over plains can be shifted by slight wind until hitting a small edge or elevation, thereby triggering a thermal. At present TherMap does not well map such locations.
Other effects: TherMap only shows the solar heating effect causing thermals on slopes. At certain locations other effects can however be stronger than the thermals, e.g. due to cloud covers, or wind, particularly at narrow valley entrances, but also where the air is cooled or moistened by lakes or ice covered surfaces.

Regions Available

Europe

Country/Region	Northwest Corner	Southeast Corner
Switzerland	48° 00'’ N / 05° 30’ E	45° 30'’ N / 11° 00’ E
Austria	48° 00'’ N / 09° 30’ E	46° 00'’ N / 16° 20’ E
French Alps	47° 30'’ N / 05° 00’ E	43° 00'’ N / 07° 30’ E
Pyrenees	43° 20'’ N / 03° 00’ W	42° 00'’ N / 02° 30’ E
Northern Apennine	45° 00'’ N / 07° 30’ E	43° 30'’ N / 12° 30’ E
Central Apennine	43° 30'’ N / 11° 30’ E	41° 00'’ N / 15° 00’ E
Slovakia	48° 00'’ N / 18° 00’ E	50° 00'’ N / 24° 00’ E

United States

Country/Region	Northwest Corner	Southeast Corner
US Sierra Nevada Very North	43° 00'’ N / 125° 00’ W	41° 00'’ N / 115° 00'’ W
US Sierra Nevada North	41° 00'’ N / 125° 00’ W	39° 00'’ N / 115° 00'’ W
US Sierra Nevada Center	39° 00'’ N / 123°30’ W	37° 00'’ N / 113°30'’ W
US Sierra Nevada South	37° 00'’ N / 122° 00’ W	35° 00'’ N / 112° 00'’ W

View/Download Maps

Country :	Depending on the flight you may have to select one or more of the countries or regions
Date :	TherMap provides maps of selected dates from the beginning of April to the middle of September (Months 4 to 9). Select the maps showing the date closest to the flight date. The map date/time is included in its file name (month-day-hrZ)
Time:	UTC is now generally used, whereby 3 map times per day have been included in the map collection, namely one for the latest full hour before the highest elevation of the sun, and two others for the beginning and the closing of the thermal day. It would of course be possible to add more maps for the timnes between these reference hours. UTC is normally also used in the flight records. Select the map closest to the time of overflight. A longer flight will therefore require several maps. This also applies to flight analyses, for which we recommend however to make use of the Google Earth overlays of TherMap.

The following table contains maps generated by TherMap 3.

Each cell on the following table represents a map of a region at a the indicated date and time. Select the one closest to your flight path. (About 6-10 Mb per JPG map). Then either double click on the field of the map to be viewed, or right click on the target field and request the map to be saved directly on your PC.

The complementary maps either show the basic topography or the slope determined view of the region.

EUROPE	Date + Time
EUROPE	Date + Time	April 01	April 25	May 20	June 20	July 20	Aug 15	Sep 10	Topography and slope maps
Switzerland	Morning	09h Z	09h Z	08hZ	08h Z	08h Z	09h Z	09h Z	Topography Slope
	Peak	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z
	Evening	15h Z	17h Z	17h Z	17h Z	17h Z	16h Z	15h Z
France Alps	Morning	10h Z	10h Z	09h Z	09h Z	09h Z	10h Z	10h Z	Topography Slope
	Peak	13h Z	13h Z	13h Z	13h Z	13h Z	13h Z	13h Z
	Evening	16h Z	17h Z	18h Z	18h Z	18h Z	17h Z	16h Z
Austria	Morning	09h Z	09h Z	08h Z	08h Z	08h Z	09h Z	10h Z	Topography Slope
	Peak	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z
	Evening	15h Z	16h Z	17h Z	17h Z	17h Z	16h Z	15h Z
Pyrenees	Morning	10h Z	10h Z	09h Z	09h Z	09h Z	10h Z	10h Z	Topography Slope
	Peak	13h Z	13h Z	13h Z	13h Z	13h Z	13h Z	13h Z
	Evening	16h Z	17h Z	18h Z	18h Z	18h Z	17h Z	16h Z
Apennine North	Morning	09h Z	09h Z	08h Z	08h Z	08h Z	09h Z	09h Z	Topography Slope
	Peak	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z
	Evening	15h Z	16h Z	17h Z	17h Z	17h Z	16H Z	15h Z
Apennine Center	Morning	09h Z	09h Z	08h Z	08h Z	08h Z	09h Z	09h Z	Topography Slope
	Peak	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z
	Evening	15h Z	16h Z	17h Z	17h Z	17h Z	16h Z	15h Z
Carpathia West	Morning	09h Z	09h Z	08h Z	08h Z	08h Z	09h Z	09h Z	Topography Slope
	Peak	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z	12h Z
	Evening	15h Z	16h Z	17h Z	17h Z	17h Z	16h Z	15h Z

USA	Date Time	April 01	April 25	May 20	June 20	July 20	Aug 15	Sep 10	>Topography and slope maps
Very North Sierra Nevada	Morning	18h Z	18h Z	17h Z	17h Z	17h Z	18h Z	18h Z	Topography Slope
	Peak	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z
	Evening	24h Z	25h Z	26h Z	26h Z	26h Z	25h Z	24h Z
North Sierra Nevada	Morning	18hZ	18h Z	17h Z	17h Z	17h Z	18h Z	18h Z	Topography Slope
	Peak	21h Z	21h Z	21h Z	21h Z	21h Z K	21h Z	21h Z
	Evening	24h Z	25h Z	26h Z	26h Z	26h Z	25h Z	24h Z
Central Sierra Nevada	Morning	18hZ	18h Z	17h Z	17h Z	17h Z	18h Z	18h Z	Topography Slope
	Peak	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z
	Evening	24h Z	25h Z	26h Z	26h Z	26h Z	25h Z	24h Z
South Sierra Nevada	Morning	18h Z	18h Z	17h U	17h Z	17h Z	18h Z	18h Z	Topography Slope
	Peak	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z	21h Z
	Evening	24h Z	25h Z	26h Z	26h Z	26h Z	25h Z	24h Z

© Wafer: All maps of this collection are provided by the copyright holder solely as an informational tool for the planning of the best course of soaring flights. In particular, airports and landing places are indicated mainly for geographical reference without guarantees about their exact location and/or their operational conditions. These maps are not intended to be used for navigation. Pilots should independently confirm all information regarding airports and landing places and other information required for navigation, and obtain an official briefing before flight. In no event shall the copyright holder or the contributors be liable for any direct or consequential damages caused by incorrect, obsolete or missing graphical or written content.

The copyright holder: Beda Sigrist, Switzerland

Viewing with Google Earth

A 3D view may facilitate the perception of a thermal landscape, as illustrated by this example. Users having installed Google Earth© on their PCs (not on tablets or smartphones) can generate such perspectives themselves and/or simulate flights in a "landscape with visible thermals". In addition actual flight records (converted to KML file format) can be superimposed to review a flight. Note that Google Earth running on Android does not yet permit to use the kmz-files.

TherMap is based on the same topographic data (SRTM) as Google Earth. It is possible to link TherMap files with Google Earth within seconds. Before doing this you should be aware of the following:

In order to avoid a significant loss in image resolution (due to a constraint of Google Earth), the original charts had to be cut into tiles of two square degrees which are therefore referred to at the lowest level of the Google selection tree. TherMap actual had to generate almost 3000 tile files for this purpose. The resulting Google selection hierarchy looks as follows

(1) TherMap3-3D> (2) Region > (3) Region+date+daytime> (4) Tile (coordinates of left lower corner)

It is crucial to never select the maps above the level of the "Region + Date + Daytime"i.e. level 3. Above this level Google overlays all maps below the level selected, e.g. all dates and daytimes of a selected region, which would be meaningless. It is however also possible to activate several adjacent regions for a specific date and daytime. Note that loading the tiles still takes a few seconds with Google Earth.

Example of how to use Google Earth:
Suppose you want to see the area around Lake Mono (US) on June 1 at 19hUTC, click on the link below: "US Maps (Sierra Nevada)" and confirm that you want to open this link with Google Earth, upon which the Google screen appears.

Under "Places" at left first click the "+" box to expand the map selection e.g. "TherMap2_USA-3D". You will see the regions available.
Then click the "+" box of "SraNevd_C" (i.e. the Sierra Nevada between 37 and 39 deg latitude).
Google then shows the dates and daytimes available for this region.
Check the empty square on the left of "SraNevd_CJun1_19hZ" to select all maps for this region ,date and time. Google then switches on the map tiles of this region and adds the list of these tiles.
Unselect the tiles you do not need. In our case these are the ones ending with 37N117W, 38N117W, 37N115W, and 38N115W, leaving the four map tiles around Mono Lake. Then zoom into them...

Google overlay picture transparency is set at 20-35 percent, in order to still perceive the underlying Google landscape. The transparency can be changed manually at tile (= lowest) level by right-clicking on the selected field, then clicking on "Properties" and finally adjusting the transparency slider on top of the property window.

Right-click on the region for which you want to download the kmz-file
on your desktop. Then click on the downloaded kmz-file to open
Google Earth showing the selection of TherMap files >

Google Earth

European Maps

Google Earth

US Maps (Sierra Nevada)

Links

SRTM download website: http://srtm.csi.cgiar.org/

Link to DWD Topterm

WMO/OSTIV: Weather Forecasting for Soaring Flight, 2009

PC-Met, Alptherm

SeeYou®: http://www.naviter.si/

Meteorological panel of OSTIV

OSTIV, B.Sigrist: Use of Topographic Elevation Models to Identify Thermal Hotspots in Alpine Areas, Technical Soaring, Vol 30, no.3 (2006)

Google Earth: http://earth.google.com

Alfred Ultsch: "Thermikstrassenkarten", Segelfliegen, 3/2010

Alpine thermal map for paragliders: http://thermal.kk7.ch

B.Sigrist: "TherMap, el mapa térmico", Parapente vuelo libre, no. 81, 10 marzo 2011

Sergio Colacevich: Sierra Nevada Great Basin TherMaps, Soaring, July 2011

Thermikkarte Deutschland, 2005

Contact: If you have any comments, suggestions, or questions, you are welcome to directly contact the author Beda Sigrist by e-m@ail.