“情绪的突然发作”可以翻译为 "a sudden outburst of emotions" 或 "a sudden emotional outburst"。
"outburst" 强调情绪的爆发或突然宣泄，带有较强的情感冲击力。
"emotions"（复数）或 "emotional"（形容词）可根据语境选择，前者更侧重情绪的多样性，后者更强调情绪的性质。
例句：He had a sudden outburst of emotions after hearing the news. （听到消息后，他情绪突然爆发。）
Her sudden emotional outburst surprised everyone in the room. （她突然的情绪发作让房间里所有人都吃了一惊。）