问题 问答题 简答题

干湿表是如何测定空气湿度的?

答案

参考答案:

利用两支球部大小形状完全相同的温度表,放在同一环境中(如百叶箱),其中一支用来测定空气温度,称为干球;

另一支球部缠上润湿的纱布,称为湿球。当空气中的水汽含量未达饱和时,湿球表面的水分不断蒸发,消耗湿球的热量而降温;同时又从流经湿球的空气中不断取得热量补给。

当湿球因蒸发而消耗的热量和从周围空气中获得的热量相平衡时,湿球温度就不再继续下降。从而维持了一相对稳定的干湿球温度差。干湿球温度差值的大小,主要与当时的空气湿度有关。空气湿度越小,湿球表面的水分蒸发越快,湿球温度降得越多,干湿球温度差就越大;反之,湿度大,湿球水分蒸发慢,湿球温度降低得少,干湿球温度差就小。根据干湿球温度值,以及其它一些因素,从理论上就可推算出当时的空气湿度来。

完形填空
完形填空

    Although it was autumn, the snow was already beginning to fall in Tibet (西藏). Our legs were so
heavy and cold that   1   felt like big pieces of ice. Have you   2   seen snowmen ride bicylces? That's
what we looked like! Along the way children who were   3   long wool coats stopped to look at us.
In the late   4   we found it was so cold that our water bottles froze (结冰). However, the lakes   5  
 like glass in the setting sun and loooked wonderful.
    Wang Wei rode in front of me as usual. She was in high spirt and I knew I didn't need to   6   her.
To climb the mountains was hard work but as we   7   us, we were surprised by the view. We seemed
to be able to see for miles, and we were so high that we found ourselves cycling through clouds. After
a while, we began going   8   the mountains. It was great fun especially as it slowly became much   9  .
At the foot of the mountains, colourful butterflies flew around us and we saw many sheep eating green
grass. Then we had to  10 . Our caps, gloves and trousers for T-shirts and shorts.
    In the early evening we stopped to  11 . We put up our tent and then we ate. Afte supper Wang Wei
went to sleep but I stayed  12 . At midnight the sky became clearer and  13  and the stars grew brighter.
As I  14  below the stars I thought about how far we had already travelled.
    We will reach Dali in Yunan Province soon, where our cousins will join us. We  15  hardly wait to see
them!

( )1. A.we       
( )2. A.never   
( )3. A.dressed in
( )4. A.morning  
( )5. A.shine  
( )6. A.follow  
( )7. A.looked at 
( )8. A.up    
( )9. A.colder  
( )10. A.charge 
( )11. A.make beds
( )12. A.alive   
( )13. A.cloudy   
( )14. A.lie    
( )15. A.may    
B.you            
B.ever       
B.put on      
B.afternoon    
B.shining     
B.encourage    
B.looked after  
B.down       
B.drier       
B.check       
B.make friends  
B.alone       
B.foggy       
B.lied       
B.can        
C.they       
C.even    
C.taken off  
C.evening   
C.shines   
C.remind  
C.looked for
C.around   
C.warmer   
C.chase    
C.make camp   
C.away    
C.noisy    
C.lay     
C.must    
D.it             
D.yet          
D.dressed up     
D.night        
D.shone        
D.discover     
D.looked around           
D.into         
D.wetter         
D.change       
D.make money     
D.awake          
D.quiet          
D.laid           
D.shall        
单项选择题