WEATHER AND CLIMATE 65 



9. Entirely apart from an ample water supply what 

 must be true of land surfaces to make irrigation for large 

 areas possible? Why is there need of national and state 

 aid in developing irrigated districts? What industries 

 are made possible in such districts? W T hat .are the ad- 

 vantages and what the disadvantages of living on irrigated 

 lands? 



10. Describe any extensive irrigating system of which 

 you have personal knowledge, or of which you have acquired 

 definite knowledge by reading. 



WEATHER AS AFFECTED BY HIGHS AND LOWS 



1. From the weather maps of Figures 27, 28, 29, 1 showing 

 the progress of typical storm areas, locate and explain the 

 significance of (a) the isotherms; (b) the isobars; (c) the 

 wind directions from a high; (d) the wind directions into 

 a low; (e) the modification of temperature of a whole region 

 by an advancing high; (/) the isotherms "running" with 

 the lows ; (g) the areas of precipitation. Explain any pre- 

 cipitation in front of an advancing high. 



2. Account for wind directions at any point not in accord 

 with the general atmospheric circulation about and into a 

 low, or out from a high. What is the significance (a) of 

 the term cyclone when applied to a low ; (6) of anti-cyclone 

 applied to a high? What conditions largely determine the 

 wind velocities reported at various points? 



1 Get from the nearest Weather Bureau Station, if possible, some daily 

 Weather Maps of recent date. Ask that those furnished be for successive 

 days during a week or more. 



