STUDIES IN NATURE 



near their centre, and the further we go out- 

 wards the lower the pressure becomes. The 

 state of the atmosphere is then called an ' anti- 

 cyclone.' Now, where the pressure is high, the 

 air will be forced away towards the regions 

 where it is low, and the new air will descend from 

 above to take its place. Therefore over the 

 high-pressure area of an anti-cyclone a column 

 of air is constantly descending from the upper 

 atmosphere, and spreading outwards over the 

 surface of the earth. 



But why should the wind blow in circles ? 

 Let us remember that the earth is like a great 

 top, always spinning on its axis, and perhaps 

 this will help us to find an explanation. If an 

 orange be placed on the table, and turned round 

 as it stands, we see that a point near the top 

 or the bottom of the orange has not got so far 

 round to go as a point near the middle of the 

 orange. So with the earth. A point nearer 

 the north or south pole has not so far to travel 

 each day as has a point further away from the 

 poles. Thus the wind which blows outwards 

 towards the south from the centre of an anti- 

 cyclone lying over north Europe, passes over 

 points on the earth which are moving faster and 

 faster the farther the wind goes. The wind 

 will therefore meet the ground as it revolves, 

 and will seem to be travelling in the opposite 

 direction. Now the earth revolves from west 

 to east, and thus the wind gets a drift from east 



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