Temperature Sensor Update

I did a calibration test for my DHT11 yesterday, and found a few problems.  I placed the room-temperature RPi and a room-temperature thermometer in the freezer, and recorded the temperatures before I put them in, and again after a few minutes.

I ran the test in 3 scenarios, one with the sensor connected directly to the RPi GPIO, one connected through the breadboard, and one with a 10k Ohm resistor included, as directed in the how-to file <https://learn.adafruit.com/dht-humidity-sensing-on-raspberry-pi-with-gdocs-logging/wiring>. Here are the results:

Run	Beginning Temperature	Beginning DHT11	Final Temperature	Final DHT11
Connected directly to GPIO	25C	29C	-11C	1C
Connected through breadboard	25C	22C	-13C	1C
With 10kOhm Resistor	24C	22C	-15C	1C

So, the beginning temperatures were much closer with the breadboard than without. Then, as was pointed out to me, the resistor helps the RPi as a failsafe.

The problem is now obviously with the final temperature.  I looked at the details on the DHT11, and found that it only has a range of 0C to 50C.  I'm not sure if I'll get negative temperatures or not, but I'd rather be safe. So, I ordered a couple of DHT22 sensors. The DHT22 has a range of -40C to 80C.  Here are the specs on the DHT22:
http://www.adafruit.com/product/385

In addition, I also ordered the BMP180 Pressure sensor. By the end of next week, I should have all the measurement sensors I need.  Here are the specs on the BMP180:
http://www.adafruit.com/products/1603

The biggest task for me now is to find out how to release the balloons.