WEATHER FORECASTS. 



313 



been divided with reference to the origins of storms and also the paths 

 of the storms. All the paths cross JSTew England, and the chart 

 shows what a harsh, changeable climate this section has. There is 

 no other region on the face of the earth, not even excepting Siberia, 

 where there are such sudden and violent changes of weather as in New 

 England. All storms that visit the United States cross New England 

 and pass off toward the St. Lawrence Gulf, if they do not die out 

 on the way. Lows move on an average at the rate of twenty-five 

 miles per hour. 



We have now seen that highs and lows have definite points of 

 origin or entrance into the country, and that they follow well-estab- 

 lished tracks. It is clear, therefore, how their location a few hours 

 in advance may be estimated. 



Highs are not usually accompanied by rain, but the temperature 

 falls in advance of them as they pass over the country. The lows, on 

 the contrary, are the storms, and usually carry rain with them. The 

 greatest rainfall is usually to the northeast of the center of the low, 

 and the low tends to move toward the point where there is the 

 heaviest rain. The temperature of the air rises in the regions to the 

 east of the low, and falls to the west of it. 



Having located the highs and lows that exist and determined 

 what paths they are likely to follow, from the laws that have been 



Fig. 6. — TiiK Barograph. 



explained, it may be seen how the direction of the wind, the occur- 

 rence of rain, and the changes in temperature can be predicted (Fig. 

 5). Eig. 5 is a reproduction of a newspaper weather map. The 

 dotted lines connect all points having the same temperature, tempera- 

 tures ten degrees apart being chosen. The full lines are lines of 

 equal barometric pressure, there being a line for each one tenth of 

 an inch difference in pressure. The arrows fly with the wind. Kain 



