Electrical Charge Distribution In A Thunderstorm (CSIR - UGC NET 2016 June | Paper code B | Q.138)

 Q138. The below cartoon exhibits a cloud during the mature stage of development of a simple convective thunderstorm. The simplest charge structure sequence in boxes. A, B, C, respectively, can be depicted as follows. 

Positive charges are shown as +++ and negative charges – – –

1. – – –, – – –, +++

2. +++, – – –, negligible positive charge

3. – – –, +++, – – –

4. Negligible positive charge, +++, – – –

Correct Ans - 2

Explanation - 

Topic - 

electrical charge distribution in a thunderstorm

• Thunderstorm always form in Cumulonimbus type of cloud. 
• when colder, supercooled liquid droplets freeze on contact with a warmer hailstone and tiny splinters of positively charged ice break off.
• These lighter, positively charged particles are then carried to the upper part of the cloud by updrafts. 
• The larger hailstones, left with a negative charge, either remain suspended in an updraft or fall toward the bottom of the cloud. 
• By this mechanism, the cold upper part of the cloud becomes positively charged, while the middle of the cloud becomes negatively charged.
• The lower part of the cloud is generally of negative and mixed charge except for an occasional positive region located in the falling precipitation near the melting level.

FIGURE -  The development of a lightning stroke. 

(a) When the negative charge near the bottom of the cloud becomes large enough to overcome the air’s resistance, a flow of electrons — the stepped leader — rushes toward the earth. 

(b) As the electrons approach the ground, a region of positive charge moves up into the air through any conducting object, such as trees, buildings, and even humans. \

(c) When the downward flow of electrons meets the upward surge of positive charge, a strong electric current — a bright return stroke — carries positive charge upward into the cloud.