Cumulus Support

how can you mesure the ground temp or what wqpment would you use

A grass thermometer, normally. And some types of weather station have these as optional extras.

witch one would recomend and were yould it get it(grass)

I don't have much experience of standard meteorological kit; as long as you got one from a reputable manufacturer, they should all be pretty much the same. This is the sort of thing: http://www.fairmountweather.com/product ... t=4&pid=30

thank you steve is there any electric ones

I found a few Googling rather than 'Steveing' -- LOL

Could not see one that would link to a Fine Offset type station though -- I do not think these stations can take other readings

I'm not aware of any (other than the add-on probes to weather stations like the Davis VP2) but I guess they probably do exist.

daj wrote:Could not see one that would link to a Fine Offset type station though -- I do not think these stations can take other readings

I think it's just the Davis and Oregon Scientific stations that allow them. Maybe even some of the much-maligned (by me) La Crosse stations...

imike,

If you only require remote readings; other than through the weather station, you coud use a system like the cheap remote indoor/outdoor digital thermometers, you can simply modify one of the remote units.
I did this to measure the water temperature in a pond filter box.

You simply take the unit apart, find the sensor (usually a small black thermistor), extent the wiring and encapsulate the thermistor in a small waterproof metal or plastic tube.

Incidentally the link Steve gave you to that site is for a 'grass' thermometer; was that what you wanted, or was it a 'ground' thermometer, actually inserted in the ground?

The same company make ground thermometers...
http://www.fairmountweather.com/product ... at=4&pid=5

The remote unit could be adapted to measure this if inserted at the end of a 12" metal tube.

Mike.

Repairman77 wrote:Incidentally the link Steve gave you to that site is for a 'grass' thermometer; was that what you wanted, or was it a 'ground' thermometer, actually inserted in the ground?

Good point - I had assumed 'grass' thermometer as these are used to measure temperatures at ground level. I'm used to the ones inserted into the ground being called 'earth' thermometers.

Been looking into this myself as the air temperature at 4 or 5 ft above ground is a fair bit higher than the ground temperature. There have been several days in the last fortnight when the ground has been freezing hard but air thermometers have shown a couple of degrees above freezing. So far the only thing I've found has been indoor/outdoor digital thermometers or very expensive temperature probes. Extending the cable to the external probe could be a problem if it uses a thermocouple as any change in metal will cause errors. I doubt thermistors would be accurate enough. If the measuring electronics could be put outdoors it might be possible to use a thermocouple type.

I'd be very interested in any other thoughts on this

Maplin do an indoor/outdoor digital thermometer http://www.maplin.co.uk/Module.aspx?ModuleNo=34932 It just might be possible to get inside this and bring out digital data to interface with a computer. They also do other similar thermometers.

This brings me to a point I have been discussing with Dave -Laindon Weather. Many of us set up our weather stations on poles or rooves - all of different heights. Shouldn't we try to get some uniformity with our sensors so that the data recorded is comparable.The met. Office suggests a height of 1.25 Metres above ground level (approx. 4 feet) for temperature sensors.I haven't worked out if height above sea level is another factor to take into account although I think it probably is.Hands up if your temperature sensor is 4 feet above ground level & also if you live at the top of Mount Everest! This however brings problems of numerous wires going from different parts of the weather station to different locations in the garden.

If this is in the wrong place - apologies.

Cheers,

Chris

The met. Office suggests a height of 1.25 Metres above ground level (approx. 4 feet) for temperature sensors

My Danish Met. Office recommends 2 metres above ground level for temperature and humidity sensors, and 1.5 metres for rain sensors (and 10 metres for wind instruments).
So much for 'standards'

Oddly, UK MetO height standard is for the enclosure (expecting a big wooden box and a stick thermometer), so you will see variations in 'standard' height.

Again - the standards were brought in as windchill was beginning to be appreciated, and so was equal to average head height.

.... but, we've all been on a better diet since then ... and so it goes on

Temp sensor should be 1.5 => 1.7m above grass. (Sea Level is not a consideration unless you are floating on it)