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The Thermal Connection. Physical Principle Temp proportional to kinetic energy (1/2mv 2 ) Thermometers measure themselves must be protected/shade - at six feet AGL (2m) type of thermometers: liquid in glass (Hg,alcohol) resistance based (change in current flow prop to T)
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The Thermal Connection • Physical Principle • Temp proportional to kinetic energy (1/2mv2) • Thermometers measure themselves • must be protected/shade - at six feet AGL (2m) • type of thermometers: • liquid in glass (Hg,alcohol) • resistance based (change in current flow prop to T) • bimetallic (thermostats) • Placement is critical! • Temperature drift is almost always upward
The Thermal Connection • Insolation warms the ground • The ground heats the air • by conduction (direct contact) • by convection (bubbles of warm air) • The air is heated from below (by IR out) • maximum temp at surface • The air absorbs UV from above • second max in temp in stratosphere • see vertical profile of atmospheric temperature
Daily Temperature diurnal cycle min in am / max in pm amplitude of cycle amount of insolation sun angle/day length latitude (low - constant) (mid & hi - varies) continent vs. maritime soil/vegetation type lag due to balance of incoming vs. outgoing Annual Temperature varies with seasons Low latitudes - small changes (due to wet/dry season) Mid latitudes - larger changes (due to coast vs inland) Hi latitudes - largest changes where most continental Lag due to heat capacity differences The Thermal Connection