Acoustic Velocity over the Temperature

set terminal dumb
unset key;
set zeroaxis;
set title "Acoustic Velocity over the Temperature";
set xlabel "Temperature [°C]"
set ylabel "acoustic velocity [m/s]"
set xrange [-20:40]
plot 331.5*sqrt(1+x/273.15) w lines,331.5 lt 0;

                                                                               
                                 Acoustic Velocity over the Temperature        
                                                                               
                         355 +---------------------------------------------+   
                             |       +      |       +       +      +  **** |   
                         350 |-+            |                       ***  +-|   
                             |              |                   ****       |   
                         345 |-+            |                ****        +-|   
                             |              |             ****             |   
                         340 |-+            |          ****              +-|   
                             |              |       ****                   |   
                         335 |-+            |    ****                    +-|   
                             |              | ****                         |   
                             |+++++++++++++++++++++++++++++++++++++++++++++|   
                         330 |-+        *** |                            +-|   
                             |       ****   |                              |   
                         325 |-+  ****      |                            +-|   
                             | ****         |                              |   
                         320 |**            |                            +-|   
                             |       +      |       +       +      +       |   
                         315 +---------------------------------------------+   
                            -20     -10     0       10      20     30      40  
                                            Temperature [°C]                  
                                                                         

set terminal dumb
unset key;
set xzeroaxis 20;
set title "Relation of the Acoustic Velocity over the Temperature";
set xlabel "Temperature [°C]";
set ylabel "rel. Acoustic Velocity [%]";
set xrange [-20:40];
plot sqrt(1+x/273.15)/sqrt(1+20/273.15)*100 w lines,100 lt 0;

                                                                               
                         Relation of the Acoustic Velocity over the Temperature
                                                                               
                            104 +------------------------------------------+   
                                |      +      |       +      +      +    **|   
                                |             |                       **** |   
                            102 |-+           |                    ****  +-|   
                                |             |                 ****       |   
                                |             |               ***          |   
                            100 |++++++++++++++++++++++++++++++++++++++++++|   
                                |             |        ****                |   
                             98 |-+           |     ****                 +-|   
                                |             |   ***                      |   
                                |             |***                         |   
                             96 |-+         ***                          +-|   
                                |        ***  |                            |   
                                |     ****    |                            |   
                             94 |-+****       |                          +-|   
                                |***          |                            |   
                                |      +      |       +      +      +      |   
                             92 +------------------------------------------+   
                               -20    -10     0       10     20     30     40  
                                             Temperature [°C]