With reference to upper-atmospheric circulation patterns, consider the following statements regarding jet streams: I. Jet streams are narrow bands of very strong winds that maintain near-geostrophic balance while encircling the globe. II. They are predominantly located near the tropopause within the upper troposphere. III. A stronger thermal contrast between adjacent air masses tends to make jet streams more sinuous and highly meandering. Which of the statements given above are correct?

With reference to the Madden-Julian Oscillation (MJO), consider the following statements: I. It is an eastward-moving tropical disturbance rather than a stationary atmospheric trough. II. It is associated with alternating phases of enhanced and suppressed cloudiness, convection and rainfall. III. It generally operates within the tropical belt between 30°N and 30°S latitudes. IV. It can influence monsoon variability as well as tropical cyclone activity. Which of the statements given above are correct?

Which of the following correctly explains the formation of clouds in the atmosphere?