A humidity test simulates the moisture-laden air found in tropical regions. There are typically two types of humidity tests, condensing and non-condensing. Condensing humidity tests consist of temperature cycling in high relative humidity air. The temperature cycling induces the moisture to condense on all surfaces of the test specimen. Additionally, the temperature cycling causes the test specimen to "breathe", pulling moisture laden air inside; it then condenses to liquid form. This is an extremely severe test for electronics. Non-condensing humidity tests are run at a constant temperature, with a high relative humidity, typically greater then 95%. This test is not as severe as the condensing test because the moisture is not in liquid form. This test is much more difficult to perform because the temperature must be tightly controlled to prevent condensation at such a relative humidity.