What aspect of radar operation can limit its effectiveness in bad weather?

Radar operation can be significantly affected by environmental conditions, particularly during bad weather, and one of the key issues is the presence of sea and rain clutter. When precipitation such as rain occurs, it can create additional echoes on the radar display, causing interference that can obscure or mask the targets you are trying to detect, like other vessels or navigational hazards.

Specifically, rain clutter refers to the radar signals reflected off raindrops that are usually much stronger than those reflected from distant objects. Similarly, sea clutter arises from the waves and surface conditions, which likewise reflect radar waves, creating a background noise that can make it difficult to differentiate between actual targets and the "clutter" caused by weather conditions. This clutter can lead to reduced detection capabilities and create false signals, complicating navigation and potentially leading to hazardous situations at sea.

Other aspects like reduced signal transmission or unsuitable frequencies can play roles in radar performance, but the direct and significant impact of sea and rain clutter in degrading the clarity and reliability of radar data during bad weather clearly demonstrates why this option stands out as the correct answer. Increased range generally relates to enhanced radar capabilities, rather than a limitation, and thus does not apply in this context.