Example 6. When measuring the atmospheric temperature T, it is found that T decreases with the height h in the ascending air, up to 11 kilometers, with a decrease of approximately $6^{\circ} \mathrm{C}$ for every kilometer ascended. At higher altitudes, the temperature remains almost constant. If the ground temperature is $19^{\circ} \mathrm{C}$, try to write the functional relationship between T and h.
Solve As shown in the figure, from the problem, we know:
1) From the ground to 11 kilometers above, the function relationship of T with h is
$$
T=19-6 h ;
$$
2) Above 11 kilometers, due to the temperature being almost constant,
therefore, we have
$$
\mathrm{T}=19^{\circ}-6^{\circ} \times 11=-47^{\circ} \mathrm{C} \text {. }
$$

Combining the above two points, we get
$$
\mathrm{T}=\left\{\begin{array}{l}
19-6 \mathrm{~h}, \quad 0 \leqslant \mathrm{~h} \leqslant 11 ; \\
-47, \mathrm{~h}>11
\end{array}\right.
$$