A Guide To The Scientific Knowledge Of Things Familiar Part 73

Q. _In what MONTHS is the barometer HIGHEST?_

A. In May and August; next to these, in June, March, September, and April.

Q. _In what MONTHS is the barometer LOWEST?_

A. In November and February; then in October, July, December, and January.

Q. _What are the DRIEST months?_

A. March and June; then May and August; then April and November.

Q. _What are the WETTEST months?_

A. October and February; then July and September; then January and December.

Q. _Why is there LESS wet from MARCH to AUGUST, than there is from August to March?_

A. Because the _heat is constantly increasing_; and the capacity of the air to absorb and retain moisture increases likewise.

Q. _Why is there MORE wet from AUGUST to MARCH, than there is from March to August?_

A. Because the _heat is constantly decreasing_, and the capacity of the air to retain moisture decreases also; so that (although it often rains) yet the air is always on the point of saturation.

Q. _Why does the mercury of a barometer RISE in a FROST?_

A. Because frost _condenses the air_; and condensed air is heavier than _rarefied_ air.

Q. _Why does the mercury of a barometer FALL in a THAW?_

A. Because the air is both _warmer_ (or more rarefied), and also filled with _vapour_.

Q. _What does a SUDDEN rise or fall of the barometer indicate?_

A. If the _rise_ be sudden, fine weather will not continue long:

If the _fall_ be sudden, foul weather will not continue long.

Q. _What sort of weather may we expect if the barometer be very FLUCTUATING?_

A. If the mercury fluctuates much, the weather will be very _changeable and unsettled_.

The FALL of the barometer.

In very _hot_ weather, the fall of the mercury denotes _thunder_.

Except in very hot weather, the sudden falling of the barometer denotes high wind.

In _frosty_ weather, the fall of the barometer denotes _thaw_.

If _wet_ weather happens _soon_ after the fall of the barometer, expect but _little_ of it.

In _wet_ weather if the barometer falls, expect much wet.

In _fair_ weather, if the barometer falls much and _remains_ low, expect much wet in a few days, and probably _wind_.

N. B. The barometer sinks lowest of all for wind and rain together, next to that for wind (except it be an east or north-east wind).

The RISE of the barometer.

In _winter_ the rise of the barometer presages _frost_.

In _frosty_ weather, the rise of the barometer presages _snow_.

If _fair_ weather happens _soon_ after the rise of the barometer, expect but _little_ of it.

In _wet_ weather, if the mercury rises high and _remains_ so, expect continued _fine_ weather in a day or two.

In wet weather, if the mercury rises suddenly very high, fine weather will not last long.

N. B. The barometer rises highest of all for north and east winds; for all _other_ winds it sinks.

If the barometer be UNSETTLED.

If the motion of the mercury be _unsettled_, expect unsettled weather.

If it stand at "MUCH RAIN" and rise to "CHANGEABLE," expects _fair weather of short continuance_.

If it stand at "FAIR" and fall to "CHANGEABLE," expect _foul_ weather.

N. B. Its motion _upwards_ indicates the approach of fine weather: its motion _downwards_ indicates the approach of foul weather.