Warm QNH

                        |  less than QFF

                        |

            ______|__________________________________MSL:  QFF = QNH if ISA

                        |           \                       /

                        |             \                    /            .. Cold QNH

                        |               \                /              |  greater than QFF

                        |                 \             /               |

                        |                  \           /                |

                        |                    \        /                 |           Aerodrome elevation (QFE)