The summer capital of Ladakh is Leh.

Explanation:
Leh is the summer capital of Ladakh. It is located in the Leh district of the Ladakh region in the Indian state of Jammu and Kashmir. Here's why Leh is considered the summer capital of Ladakh:

Location:
- Leh is situated at an altitude of about 3,500 meters (11,500 feet) above sea level in the Leh district.
- It lies in the Indus Valley and is surrounded by the majestic Himalayas, making it a picturesque location.

Tourist Attraction:
- Leh is a popular tourist destination and serves as the gateway to Ladakh.
- It attracts visitors from around the world due to its stunning landscapes, ancient Buddhist monasteries, and adventure activities like trekking and mountaineering.
- The town is known for its unique Tibetan-Buddhist culture and architecture, with numerous monasteries and palaces dotting the landscape.

Climate:
- Leh experiences extreme weather conditions, with cold winters and pleasant summers.
- The region remains inaccessible during winter due to heavy snowfall, which is why Leh becomes the summer capital.
- During the summer months, the weather is relatively mild and pleasant, making it the ideal time for tourism activities.

Infrastructure:
- Leh has well-developed infrastructure to cater to the needs of tourists during the summer season.
- It has a range of accommodation options, including hotels, guesthouses, and homestays.
- The town has a bustling market where visitors can find local handicrafts, Tibetan artifacts, and traditional clothing.

Accessibility:
- Leh is well-connected to major cities in India through air and road networks.
- The Kushok Bakula Rimpochee Airport in Leh has regular flights from Delhi, Srinagar, and other cities.
- The town is also connected to the rest of Ladakh and neighboring regions through a network of roads and highways.

In conclusion, Leh is the summer capital of Ladakh due to its favorable climate, stunning landscapes, tourist attractions, and well-developed infrastructure.