MOSCOW, DEC. 12 -- One of the last scenes of the summit in Washington was the most memorable for many Soviet citizens watching on television: the general secretary of their Communist Party was jumping out of a black limousine on a Washington street corner and wading into a crowd of Americans.

Shown here last night, just as Mikhail Gorbachev was landing in Moscow, the street scene captured what came across here as the summit's upbeat, informal mood. Gorbachev was smiling and waving, his KGB bodyguards seemed in shock. But more significantly, the mostly young, well-dressed Americans obviously were beside themselves with delight at meeting the Soviet superstar.

Soviets who already were aware of the rising interest in their country, and the changes Gorbachev is trying to bring about here, said the impact of his personality on foreigners showed through for the first time last week.

There was Gorbachev -- fielding President Reagan's Russian proverbs at the signing ceremony, holding forth before the American establishment, scolding the foreign press, singing "Moscow Nights" with his wife Raisa in the White House. Then there was the revelation before a group of prominent Americans that the couple had spent a summer holiday in Italy in 1971.

For Soviet citizens, most of whom have never been out of their country, gatherings of American businessmen or American publishers -- or what one Soviet official called the American "intelligentsia" -- can sound like awesome affairs. Gorbachev's apparent ease before these groups was commented upon as a national asset.

"I thought he carried himself off beautifully," said Vadim, a 34-year-old teacher. "The fact is we don't have another one like him, and haven't in a long time."

Gorbachev's performance in Washington could strengthen his popularity at home as the country is preparing the first stage of major economic change. It could also help restore some of the faith in Gorbachev's leadership lost in the shock of the sudden downfall of Moscow party boss Boris Yeltsin last month.

Soviet observers took note of the makeup of the sizable team of journalists, writers and scientists that Gorbachev took with him to Washington, which reflected a strong tilt toward reformers and intellectuals.

To the home audience, Gorbachev's verbal agility, humor and self-confidence were among the first characteristics noted as distinguishing him from his more stolid, stiff predecessors. Over the last 2 1/2 years, people here have become used to his character. But displayed before an international audience, those same traits once again invite comparisons flattering to the new leader -- and by extension, his countrymen.

As one Gorbachev admirer put it, "Sometimes we get tired of him lecturing us, but when he lectures Americans that is another matter: I thought he was right."

One senior western diplomat conjectured on whether Gorbachev's cheerful informality might not irk Soviet conservatives, who are still dubious of Reagan and U.S. motives, and are generally sticklers for protocol. "I wonder how people in Omsk look at the scene of the general secretary singing in the White House," the diplomat said. "I suppose we will never know."

But a number of Soviets, asked about the scene of the Gorbachevs singing along with Van Cliburn, said they were pleased. "It had a Russian feel to it," said one television viewer.

The summit's warm atmosphere and optimistic conclusion seemed to be reflected in Gorbachev's press conference, most of which was aired here last night and published in today's newspapers. Some of the sharper questions and comments were left intact, including the query about last week's demonstration against Kremlin emigration policies in front of the Soviet Foreign Ministry.

Gorbachev's answer, which squarely placed law and order above individual rights, expressed a view that is widely shared here, judging from the official and unofficial reaction to street protests.

Several Soviets today said they were struck by Gorbachev's stated determination to bring about a lasting change in U.S.-Soviet relations. "Everybody understands that the time has come to turn the last page of confrontation and begin a new stage," he said. "There are very powerful imperatives, I believe, and should be reflected in the policies of our governments."

Although Soviet rhetoric has always called for peaceful coexistence, many noted the force of Gorbachev's remarks. "He seemed so certain, so convincing," was one comment. "Do you think he means it?"

The details of the wins and losses on the arms control balance sheet may be of less interest to the broader Soviet public than the signing of the treaty to eliminate medium- and shorter-range nuclear weapons. After years of what in the early 1980s amounted to a virtual war scare, the idea of anything that cuts weapons and reduces tensions is widely welcomed here -- as was shown in a spate of recent polls.

But mostly it was the enthusiasm of Washington's welcome that had Soviets here surprised. Tonight on the evening news, Washington correspondent Vladimir Dunayev said the visit had virtually transformed the city, which he said was known for the reserved character of its bureaucrats. "I didn't recognize Washington," he said, describing the crowds on the streets, the smiles and the cheering.

Yesterday, the Communist Party newspaper Pravda noted positive comments coming from The New York Times about prospects for further, deeper cuts in nuclear arsenals, as a result of the summit. This, noted Pravda, was remarkable given its source, which is "no anti-war leaflet or left-wing press." On the contrary, Pravda said, "it was written in a solid bourgeois newspaper. One can say, the mouthpiece of ruling and business America."

The state-controlled press withheld further comment today on the summit's results, printing only reams of official texts and speeches from Washington and East Berlin, where Gorbachev made a stopover.