Simulating fractional Brownian motion signal is added to the ideal temperature ramp structure. Using the conditional sample technique, and Donoho and Johnostone threshold method, the ramp signal is successfully identified and separated. This method is applied to the actual atmospheric temperature data. The analysis shows that there are the temperature ramp structure in actual atmosphere, and the period is about 30 seconds. Under different stability condition, the form of ramp structure may be different. And the wavelet transform can identify the temperature ramp structure efficiently.