Earth Study 855 



water as it is boiling. Notice that near its spout there is no mist, but what 

 we call steam is formed beyond this. Why is this so? What is steam? 

 Why does water boil away ? Do kettles boil dry sooner on some days than 

 on others ? Why ? 



4. If the water disappears in the atmosphere where does it go? Why 

 do we say "the weather is damp" ? What force is it that wrings the water 

 out of the atmosphere? 



5. Why does the breath of a horse show as a mist on a cold day? 

 Why do persons who wear spectacles find their glasses covered with mist 



Forms of hoar frost. 

 Photo by W. A. Bentley. 



as soon as they enter a warm room after having been out in the cold ? Why 

 do the window-panes become covered with mist during cold weather ? Is 

 the mist on the outside or on the inside ? Why does steam show as a white 

 mist? Why does the ice pitcher, on a warm day, become covered on the 

 outside with drops of water ? Would thi s happen on a cold day ? Why not ? 



6. Why, when the water is invisible in the atmosphere, does it become 

 visible as clouds ? What causes the lower edges of cumulus clouds to be 

 so level? What is fog? Why do clouds occur on mountain peaks? 

 What causes rain ? 



7. What causes dew to form? When the grass is covered with 

 dew, are the leaves of the higher trees likewise covered ? Why not ? 

 What kind of weather must we have in order to have dewy nights ? What 

 must be the atmosphere of the air in relation to that of the ground in 

 order to condense the dew? Does dew form on windy nights? Why 

 not? Does all dew come from the air, or does some of it come from the 

 ground through the plants ? Why is not this water, pumped up by the 

 plants, evaporated? 



8. What happens to the dew if the weather becomes freezing during the 

 night? What is hoar frost? Why should water change form when it is 

 frozen ? How many forms of frost crystals can you find on the grass on a 

 frosty morning? 



